diff --git a/examples/workflow_by_code_gru.py b/examples/workflow_by_code_gru.py
index 52d3c451a..06fea1511 100755
--- a/examples/workflow_by_code_gru.py
+++ b/examples/workflow_by_code_gru.py
@@ -87,14 +87,8 @@ if __name__ == "__main__":
                 },
                 "segments": {
                     "train": ("2008-01-01", "2014-12-31"),
-                    "valid": (
-                        "2015-01-01",
-                        "2016-12-31",
-                    ),
-                    "test": (
-                        "2017-01-01",
-                        "2020-08-01",
-                    ),
+                    "valid": ("2015-01-01", "2016-12-31"),
+                    "test": ("2017-01-01", "2020-08-01"),
                 },
             },
         }
diff --git a/examples/workflow_by_code_xgboost.py b/examples/workflow_by_code_xgboost.py
index 8883bacee..94b43f449 100755
--- a/examples/workflow_by_code_xgboost.py
+++ b/examples/workflow_by_code_xgboost.py
@@ -85,14 +85,8 @@ if __name__ == "__main__":
                 },
                 "segments": {
                     "train": ("2008-01-01", "2014-12-31"),
-                    "valid": (
-                        "2015-01-01",
-                        "2016-12-31",
-                    ),
-                    "test": (
-                        "2017-01-01",
-                        "2020-08-01",
-                    ),
+                    "valid": ("2015-01-01", "2016-12-31"),
+                    "test": ("2017-01-01", "2020-08-01"),
                 },
             },
         }
diff --git a/qlib/__init__.py b/qlib/__init__.py
index b26ac986d..7fe7e79dc 100644
--- a/qlib/__init__.py
+++ b/qlib/__init__.py
@@ -11,6 +11,7 @@ import re
 import subprocess
 import platform
 import yaml
+import atexit
 from pathlib import Path
 
 from .utils import can_use_cache, init_instance_by_config, get_module_by_module_path
@@ -63,12 +64,10 @@ def init(default_conf="client", **kwargs):
         if not os.path.exists(C["provider_uri"]):
             if C["auto_mount"]:
                 LOG.error(
-                    "Invalid provider uri: {}, please check if a valid provider uri has been set. This path does not exist.".format(
-                        C["provider_uri"]
-                    )
+                    f"Invalid provider uri: {C['provider_uri']}, please check if a valid provider uri has been set. This path does not exist."
                 )
             else:
-                LOG.warning("auto_path is False, please make sure {} is mounted".format(C["mount_path"]))
+                LOG.warning(f"auto_path is False, please make sure {C['mount_path']} is mounted")
     elif C.get_uri_type() == QlibConfig.NFS_URI:
         _mount_nfs_uri(C)
     else:
@@ -83,10 +82,11 @@ def init(default_conf="client", **kwargs):
         LOG.info(f"flask_server={C['flask_server']}, flask_port={C['flask_port']}")
 
     # set up QlibRecorder
-    module = get_module_by_module_path("qlib.workflow.expm")
-    exp_manager = init_instance_by_config(C["exp_manager"], module)
+    exp_manager = init_instance_by_config(C["exp_manager"])
     qr = QlibRecorder(exp_manager)
     R.register(qr)
+    # clean up experiment when python program ends
+    atexit.register(R.end_exp, status="FAILED")  # will not take effect if experiment ends
 
 
 def _mount_nfs_uri(C):
@@ -102,9 +102,7 @@ def _mount_nfs_uri(C):
     if not C["auto_mount"]:
         if not os.path.exists(C["mount_path"]):
             raise FileNotFoundError(
-                "Invalid mount path: {}! Please mount manually: {} or Set init parameter `auto_mount=True`".format(
-                    C["mount_path"], mount_command
-                )
+                f"Invalid mount path: {C['mount_path']}! Please mount manually: {mount_command} or Set init parameter `auto_mount=True`"
             )
     else:
         # Judging system type
@@ -161,9 +159,7 @@ def _mount_nfs_uri(C):
                     os.makedirs(C["mount_path"], exist_ok=True)
                 except Exception:
                     raise OSError(
-                        "Failed to create directory {}, please create {} manually!".format(
-                            C["mount_path"], C["mount_path"]
-                        )
+                        f"Failed to create directory {C['mount_path']}, please create {C['mount_path']} manually!"
                     )
 
                 # check nfs-common
@@ -175,17 +171,15 @@ def _mount_nfs_uri(C):
                 command_status = os.system(mount_command)
                 if command_status == 256:
                     raise OSError(
-                        "mount {} on {} error! Needs SUDO! Please mount manually: {}".format(
-                            C["provider_uri"], C["mount_path"], mount_command
-                        )
+                        f"mount {C['provider_uri']} on {C['mount_path']} error! Needs SUDO! Please mount manually: {mount_command}"
                     )
                 elif command_status == 32512:
                     # LOG.error("Command error")
-                    raise OSError("mount {} on {} error! Command error".format(C["provider_uri"], C["mount_path"]))
+                    raise OSError(f"mount {C['provider_uri']} on {C['mount_path']} error! Command error")
                 elif command_status == 0:
                     LOG.info("Mount finished")
             else:
-                LOG.warning("{} on {} is already mounted".format(_remote_uri, _mount_path))
+                LOG.warning(f"{_remote_uri} on {_mount_path} is already mounted")
 
 
 def init_from_yaml_conf(conf_path):
diff --git a/qlib/config.py b/qlib/config.py
index 31acfc535..6c744a9f0 100644
--- a/qlib/config.py
+++ b/qlib/config.py
@@ -126,8 +126,14 @@ _default_config = {
         "loggers": {"qlib": {"level": "DEBUG", "handlers": ["console"]}},
     },
     # Defatult config for experiment manager
-    "exp_manager": {"class": "MLflowExpManager", "kwargs": {}},
-    "exp_uri": str(Path(os.getcwd()).resolve() / "mlruns"),
+    "exp_manager": {
+        "class": "MLflowExpManager",
+        "module_path": "qlib.workflow.expm",
+        "kwargs": {
+            "uri": str(Path(os.getcwd()).resolve() / "mlruns"),
+            "default_exp_name": "Experiment",
+        },
+    },
 }
 
 MODE_CONF = {
diff --git a/qlib/contrib/model/pytorch_gru.py b/qlib/contrib/model/pytorch_gru.py
index fb422f491..464cd9ba0 100755
--- a/qlib/contrib/model/pytorch_gru.py
+++ b/qlib/contrib/model/pytorch_gru.py
@@ -294,7 +294,6 @@ class GRU(Model):
         return pd.Series(preds, index=index)
 
 
-
 class AverageMeter(object):
     """Computes and stores the average and current value"""
 
diff --git a/qlib/workflow/__init__.py b/qlib/workflow/__init__.py
index b801da880..978e45c27 100644
--- a/qlib/workflow/__init__.py
+++ b/qlib/workflow/__init__.py
@@ -4,20 +4,51 @@
 from contextlib import contextmanager
 from .expm import MLflowExpManager
 from ..utils import Wrapper
-from ..config import C
 
 
 class QlibRecorder:
     """
     A global system that helps to manage the experiments.
+
+    The components of the system:
+    1) ExperimentManager: a class managing experiments.
+    2) Experiment: a class of experiment, and each instance of it is responsible for a single experiment.
+    3) Recorder: a class of recorder, and each instance of it is responsible for a single run.
+
+    The general structure of the system:
+    ExperimentManager
+        - Experiment 1
+            - Recorder 1
+            - Recorder 2
+            - ...
+        - Experiment 2
+            - ...
+        - ...
+
     """
 
     def __init__(self, exp_manager):
         self.exp_manager = exp_manager
-        self.uri = C["exp_uri"]
 
     @contextmanager
     def start(self, experiment_name):
+        """
+        Method to start an experiment. This method can only be called within a Python's `with` statement.
+
+        Use case:
+        ---------
+        ```
+        with R.start('test'):
+            model.fit(dataset)
+            R.log...
+            ... # further operations
+        ```
+
+        Parameters
+        ----------
+        experiment_name : str
+            name of the experiment one wants to start.
+        """
         run = self.start_exp(experiment_name)
         try:
             yield run
@@ -26,44 +57,425 @@ class QlibRecorder:
             raise e
         self.end_exp("FINISHED")
 
-    def start_exp(self, experiment_name=None):
-        return self.exp_manager.start_exp(experiment_name, self.uri)
+    def start_exp(self, experiment_name=None, uri=None):
+        """
+        Lower leverl method for starting an experiment. When use this method, one should end the experiment manually
+        and the status of the recorder may not be handled properly.
+
+        Use case:
+        ---------
+        ```
+        R.start_exp(experiment_name='test')
+        ... # further operations
+        R.end_exp('FINISHED')
+        ```
+
+        Parameters
+        ----------
+        experiment_name : str
+            the name of the experiment to be started
+        uri : str
+            the tracking uri of the experiment, where all the artifacts/metrics etc. will be stored.
+
+        Returns
+        -------
+        An experiment instance being started.
+        """
+        return self.exp_manager.start_exp(experiment_name, uri)
 
     def end_exp(self, status):
+        """
+        Method for ending an experiment manually. It will end the current active experiment, as well as its
+        active recorder with the specified `status` type.
+
+        Use case:
+        ---------
+        ```
+        R.start_exp(experiment_name='test')
+        ... # further operations
+        R.end_exp('FINISHED')
+        ```
+
+        Parameters
+        ----------
+        status : str
+            The status of a recorder, which can be SCHEDULED, RUNNING, FINISHED, FAILED.
+        """
         self.exp_manager.end_exp(status)
 
     def search_records(self, experiment_ids, **kwargs):
+        """
+        Get a pandas DataFrame of records that fit the search criteria.
+
+        Use case:
+        ---------
+        ```
+        R.log_metrics(m=2.50, step=0)
+        records = R.search_runs([experiment_id], order_by=["metrics.m DESC"])
+        ```
+
+        Parameters
+        ----------
+        experiment_ids : list
+            list of experiment IDs.
+        filter_string : str
+            filter query string, defaults to searching all runs.
+        run_view_type : int
+            one of enum values ACTIVE_ONLY, DELETED_ONLY, or ALL (e.g. in mlflow.entities.ViewType).
+        max_results  : int
+            the maximum number of runs to put in the dataframe.
+        order_by : list
+            list of columns to order by (e.g., “metrics.rmse”).
+
+        Returns
+        -------
+        A pandas.DataFrame of records, where each metric, parameter, and tag
+        are expanded into their own columns named metrics.*, params.*, and tags.*
+        respectively. For records that don't have a particular metric, parameter, or tag, their
+        value will be (NumPy) Nan, None, or None respectively.
+        """
         return self.exp_manager.search_records(experiment_ids, **kwargs)
 
-    def get_exp(self, experiment_id=None, experiment_name=None):
-        return self.exp_manager.get_exp(experiment_id, experiment_name)
+    def list_experiments(self):
+        """
+        Method for listing all the existing experiments (except for those being deleted.)
 
-    def delete_exp(self, experiment_id):
-        self.exp_manager.delete_exp(experiment_id)
+        Use case:
+        ---------
+        ```
+        exps = R.list_experiments()
+        ```
+
+        Returns
+        -------
+        A dictionary (name -> experiment) of experiments information that being stored.
+        """
+        return self.exp_manager.list_experiments()
+
+    def list_recorders(self, experiment_id=None, experiment_name=None):
+        """
+        Method for listing all the recorders of experiment with given id or name.
+
+        Use case:
+        ---------
+        ```
+        recorders = R.list_recorders(experiment_name='test')
+        ```
+
+        Parameters
+        ----------
+        experiment_id : str
+            id of the experiment.
+        experiment_name : str
+            name of the experiment.
+
+        Returns
+        -------
+        A dictionary (id -> recorder) of recorder information that being stored.
+        """
+        return self.get_exp(experiment_id, experiment_name).list_recorders()
+
+    def get_exp(self, experiment_id=None, experiment_name=None, create=True):
+        """
+        Method for retrieving an experiment with given id or name. Once the `create` argument is set to
+        True, if no valid experiment is found, this method will create one for you. Otherwise, it will
+        only retrieve a specific experiment or raise an Error.
+
+        If `create` is True:
+            If R's running:
+                1) no id or name specified, return the active experiment.
+                2) if id or name is specified, return the specified experiment. If no such exp found,
+                create a new experiment with given id or name.
+            If R's not running:
+                1) no id or name specified, create a default experiment.
+                2) if id or name is specified, return the specified experiment. If no such exp found,
+                create a new experiment with given id or name.
+        Else If `create` is False:
+            If R's running:
+                1) no id or name specified, return the active experiment.
+                2) if id or name is specified, return the specified experiment. If no such exp found,
+                raise Error.
+            If R's not running:
+                1) no id or name specified, raise Error.
+                2) if id or name is specified, return the specified experiment. If no such exp found,
+                raise Error.
+
+        Use case:
+        ---------
+        ```
+        # Case 1
+        with R.start('test'):
+            exp = R.get_exp()
+            recorders = exp.list_recorders()
+
+        # Case 2
+        with R.start('test'):
+            exp = R.get_exp('test1')
+
+        # Case 3
+        exp = R.get_exp() -> a default experiment.
+
+        # Case 4
+        exp = R.get_exp(experiment_name='test')
+
+        # Case 5
+        exp = R.get_exp(create=False) -> Error
+        ```
+
+        Parameters
+        ----------
+        experiment_id : str
+            id of the experiment.
+        experiment_name : str
+            name of the experiment.
+        create : boolean
+            decide whether to create an default experiment.
+
+        Returns
+        -------
+        An experiment instance with given id or name.
+        """
+        return self.exp_manager.get_exp(experiment_id, experiment_name, create)
+
+    def delete_exp(self, experiment_id=None, experiment_name=None):
+        """
+        Method for deleting the experiment with given id or name. At least one of id or name must be given,
+        otherwise, error will occur.
+
+        Use case:
+        ---------
+        ```
+        R.delete_exp(experiment_name='test')
+        ```
+
+        Parameters
+        ----------
+        experiment_id : str
+            id of the experiment.
+        experiment_name : str
+            name of the experiment.
+        """
+        self.exp_manager.delete_exp(experiment_id, experiment_name)
 
     def get_uri(self):
+        """
+        Method for retrieving the uri of current experiment manager.
+
+        Use case:
+        ---------
+        ```
+        uri = R.get_uri()
+        ```
+
+        Returns
+        -------
+        The uri of current experiment manager.
+        """
         return self.exp_manager.get_uri()
 
-    def get_recorder(self, recorder_id=None, recorder_name=None):
-        return self.exp_manager.active_experiment.get_recorder(recorder_id, recorder_name)
+    def get_recorder(self, recorder_id=None, recorder_name=None, experiment_name=None):
+        """
+        Method for retrieving a recorder.
+
+        If R's running: 1) no id or name specified, return the active recorder. 2) if id or name is
+        specified, return the specified recorder.
+        If R's not running: 1) no id or name specified, raise Error. 2) if id or name is specified,
+        and the corresponding experiment_name must be given, return the specified recorder. Otherwise,
+        raise Error.
+
+        The recorder can be used for further process such as `save_object`, `load_object`, `log_params`,
+        `log_metrics`, etc.
+
+        Use case:
+        ---------
+        ```
+        # Case 1
+        with R.start('test'):
+            recorder = R.get_recorder()
+
+        # Case 2
+        with R.start('test'):
+            recorder = R.get_recorder(recorder_id='2e7a4efd66574fa49039e00ffaefa99d')
+
+        # Case 3
+        recorder = R.get_recorder() -> Error
+
+        # Case 4
+        recorder = R.get_recorder(recorder_id='2e7a4efd66574fa49039e00ffaefa99d') -> Error
+
+        # Case 5
+        recorder = R.get_recorder(recorder_id='2e7a4efd66574fa49039e00ffaefa99d', experiment_name='test')
+        ```
+
+        Parameters
+        ----------
+        recorder_id : str
+            id of the recorder.
+        recorder_name : str
+            name of the recorder.
+        experiment_name : str
+            name of the experiment.
+
+
+        Returns
+        -------
+        A recorder instance.
+        """
+        return self.get_exp(experiment_name=experiment_name, create=False).get_recorder(
+            recorder_id, recorder_name, create=False
+        )
+
+    def delete_recorder(self, recorder_id=None, recorder_name=None):
+        """
+        Method for deleting the recorders with given id or name. At least one of id or name must be given,
+        otherwise, error will occur.
+
+        Use case:
+        ---------
+        ```
+        R.delete_recorder(recorder_id='2e7a4efd66574fa49039e00ffaefa99d')
+        ```
+
+        Parameters
+        ----------
+        recorder_id : str
+            id of the experiment.
+        recorder_name : str
+            name of the experiment.
+        """
+        self.get_exp().delete_recorder(recorder_id, recorder_name)
 
     def save_objects(self, local_path=None, artifact_path=None, **kwargs):
-        self.exp_manager.active_experiment.active_recorder.save_objects(local_path, artifact_path, **kwargs)
+        """
+        Method for saving objects as artifacts in the experiment to the uri. It supports either saving
+        from a local file/directory, or directly saving objects.
 
-    def load_object(self, name):
-        return self.exp_manager.active_experiment.active_recorder.load_object(name)
+        If R's running: it will save the objects through the running recorder.
+        If R's not running: the system will create a default experiment, and a new recorder and
+        save objects under it.
+
+        If one wants to save objects with a specific recorder. It is recommended to first
+        get the specific recorder through `get_recorder` API and use the recorder the save objects.
+        The supported arguments are the same as this method.
+
+        Use case:
+        ---------
+        ```
+        # Case 1
+        with R.start('test'):
+            pred = model.predict(dataset)
+            R.save_objects(data=pred, name='pred.pkl', artifact_path='prediction')
+
+        # Case 2
+        with R.start('test'):
+            pred1 = model1.predict(dataset)
+            pred2 = model2.predict(dataset)
+            dn_list = [(pred1, 'pred1.pkl'), (pred2, 'pred2.pkl')]
+            R.save_objects(data_name_list=dn_list)
+
+        # Case 3
+        with R.start('test'):
+            R.save_objects(local_path='results/pred.pkl')
+        ```
+
+        Parameters
+        ----------
+        data : any type
+            the data to be saved.
+        name : str
+            name of the file to be saved.
+        data_name_list : list
+            list of (data, name) pairs
+        local_path : str
+            if provided, them save the file or directory to the artifact URI.
+        artifact_path=None : str
+            the relative path for the artifact to be stored in the URI.
+        """
+        self.get_exp().get_recorder().save_objects(local_path, artifact_path, **kwargs)
 
     def log_params(self, **kwargs):
-        self.exp_manager.active_experiment.active_recorder.log_params(**kwargs)
+        """
+        Method for logging parameters during an experiment.
+
+        If R's running: it will log parameters through the running recorder.
+        If R's not running: the system will create a default experiment as well as a new recorder, and
+        log parameters under it.
+
+        One can also log to a specific recorder after getting it with `get_recorder` API.
+
+        Use case:
+        ---------
+        ```
+        # Case 1
+        with R.start('test'):
+            R.log_params(learning_rate=0.01)
+
+        # Case 2
+        R.log_params(learning_rate=0.01)
+        ```
+
+        Parameters
+        ----------
+        keyword argument:
+            name1=value1, name2=value2, ...
+        """
+        self.get_exp().get_recorder().log_params(**kwargs)
 
     def log_metrics(self, step=None, **kwargs):
-        self.exp_manager.active_experiment.active_recorder.log_metrics(step, **kwargs)
+        """
+        Method for logging metrics during an experiment.
+
+        If R's running: it will log metrics through the running recorder.
+        If R's not running: the system will create a default experiment as well as a new recorder, and
+        log metrics under it.
+
+        One can also log to a specific recorder after getting it with `get_recorder` API.
+
+        Use case:
+        ---------
+        ```
+        # Case 1
+        with R.start('test'):
+            R.log_metrics(train_loss=0.33, step=1)
+
+        # Case 2
+        R.log_metrics(train_loss=0.33, step=1)
+        ```
+
+        Parameters
+        ----------
+        keyword argument:
+            name1=value1, name2=value2, ...
+        """
+        self.get_exp().get_recorder().log_metrics(step, **kwargs)
 
     def set_tags(self, **kwargs):
-        self.exp_manager.active_experiment.active_recorder.set_tags(**kwargs)
+        """
+        Method for setting tags for a recorder.
 
-    def delete_tag(self, *key):
-        self.exp_manager.active_experiment.active_recorder.delete_tag(*key)
+        If R's running: it will set tags through the running recorder.
+        If R's not running: the system will create a default experiment as well as a new recorder, and
+        set the tags under it.
+
+        One can also set the tag to a specific recorder after getting it with `get_recorder` API.
+
+        Use case:
+        ---------
+        ```
+        # Case 1
+        with R.start('test'):
+            R.set_tags(release_version=2.2.0)
+
+        # Case 2
+        R.set_tags(release_version=2.2.0)
+        ```
+
+        Parameters
+        ----------
+        keyword argument:
+            name1=value1, name2=value2, ...
+        """
+        self.get_exp().get_recorder().set_tags(**kwargs)
 
 
 # global record
diff --git a/qlib/workflow/exp.py b/qlib/workflow/exp.py
index 432497fda..005b113df 100644
--- a/qlib/workflow/exp.py
+++ b/qlib/workflow/exp.py
@@ -2,6 +2,7 @@
 # Licensed under the MIT License.
 
 import mlflow
+from datetime import datetime
 from pathlib import Path
 from .recorder import MLflowRecorder
 from ..log import get_module_logger
@@ -11,12 +12,13 @@ logger = get_module_logger("workflow", "INFO")
 
 class Experiment:
     """
-    Thie is the `Experiment` class for each experiment being run. The API is designed
+    Thie is the `Experiment` class for each experiment being run. The API is designed similar to mlflow.
+    (The link: https://mlflow.org/docs/latest/python_api/mlflow.html)
     """
 
-    def __init__(self):
-        self.name = None
-        self.id = None
+    def __init__(self, id, name):
+        self.id = id
+        self.name = name
         self.active_recorder = None  # only one recorder can running each time
         self.recorders = dict()  # recorder id -> object
 
@@ -32,16 +34,14 @@ class Experiment:
         output["class"] = "Experiment"
         output["id"] = self.id
         output["name"] = self.name
-        output["active_recorder"] = self.active_recorder.id
+        output["active_recorder"] = self.active_recorder.id if self.active_recorder is not None else None
         output["recorders"] = list(self.recorders.keys())
+        return output
 
     def start(self):
         """
         Start the experiment.
 
-        Parameters
-        ----------
-
         Returns
         -------
         A running recorder instance.
@@ -63,9 +63,6 @@ class Experiment:
         """
         Create a recorder for each experiment.
 
-        Parameters
-        ----------
-
         Returns
         -------
         A recorder object.
@@ -124,13 +121,31 @@ class Experiment:
         """
         raise NotImplementedError(f"Please implement the `get_recorder` method.")
 
+    def list_recorders(self):
+        """
+        List all the existing recorders of this experiment.
+
+        Returns
+        -------
+        A dictionary (id -> recorder) of recorder information that being stored.
+        """
+        raise NotImplementedError(f"Please implement the `list_recorders` method.")
+
 
 class MLflowExperiment(Experiment):
     """
     Use mlflow to implement Experiment.
     """
 
+    def __init__(self, id, name, uri):
+        super(MLflowExperiment, self).__init__(id, name)
+        self._uri = uri
+        self._total_recorders = 0
+        self._default_name = None
+
     def start(self):
+        # get all the recorders of the experiment
+        self.recorders = self.list_recorders()
         # set up recorder
         recorder = self.create_recorder()
         self.active_recorder = recorder
@@ -138,17 +153,22 @@ class MLflowExperiment(Experiment):
         run = self.active_recorder.start_run()
         # store the recorder
         self.recorders[self.active_recorder.id] = recorder
+        self._total_recorders += 1  # update recorder num
+        logger.info(f"Experiment {self.id} starts running ...")
+
         return self.active_recorder
 
     def end(self, status):
         if self.active_recorder is not None:
             self.active_recorder.end_run(status)
             self.active_recorder = None
+            self._total_recorders -= 1
 
     def create_recorder(self):
         num = len(self.recorders)
         name = "Recorder_{}".format(num + 1)
-        recorder = MLflowRecorder(name, self.id)
+        recorder = MLflowRecorder(name, self.id, self._uri)
+
         return recorder
 
     def search_records(self, **kwargs):
@@ -156,21 +176,92 @@ class MLflowExperiment(Experiment):
         run_view_type = 1 if kwargs.get("run_view_type") is None else kwargs.get("run_view_type")
         max_results = 100000 if kwargs.get("max_results") is None else kwargs.get("max_results")
         order_by = kwargs.get("order_by")
+
         return mlflow.search_runs([self.id], filter_string, run_view_type, max_results, order_by)
 
-    def delete_recorder(self, recorder_id):
-        mlflow.delete_run(recorder_id)
-        self.recorders = [r for r in self.recorders if r.id == recorder_id]
+    def delete_recorder(self, recorder_id=None, recorder_name=None):
+        assert (
+            recorder_id is not None or recorder_name is not None
+        ), "Please input a valid recorder id or name before deleting."
+        try:
+            if recorder_id is not None:
+                mlflow.delete_run(recorder_id)
+                self.recorders = [r for r in self.recorders if r == recorder_id]
+            else:
+                for r in self.recorders:
+                    if self.recorders[r].name == recorder_name:
+                        recorder_id = r
+                        break
+                mlflow.delete_run(recorder_id)
+        except:
+            raise Exception(
+                "Something went wrong when deleting recorder. Please check if the name/id of the recorder is correct."
+            )
 
-    def get_recorder(self, recorder_id=None, recorder_name=None):
-        if recorder_id is not None:
-            return self.recorders[recorder_id]
-        elif recorder_name is not None:
-            for rid in self.recorders:
-                if self.recorders[rid].name == recorder_name:
-                    return self.recorders[rid]
-        elif self.active_recorder is None:
-            raise Exception("No valid active recorder exists. Please make sure the experiment is running.")
+    def get_recorder(self, recorder_id=None, recorder_name=None, create=True):
+        if recorder_id is None and recorder_name is None:
+            if self.active_recorder:
+                return self.active_recorder
+            else:
+                if create:
+                    self.start()
+                    logger.warning(
+                        f"Recorder {self.active_recorder.id} is running under the experiment with name {self.name}..."
+                    )
+                    return self.active_recorder
+                else:
+                    raise Exception(
+                        "Something went wrong when retrieving recorders. Please check if QlibRecorder is running or the name/id of the recorder is correct."
+                    )
         else:
-            logger.info("No experiment id or name is given. Return the current active experiment.")
-            return self.active_recorder
+            if recorder_id is not None:
+                if recorder_id in self.recorders:
+                    return self.recorders[recorder_id]
+                else:
+                    # mlflow does not support create a run with given id
+                    raise Exception(
+                        "Something went wrong when retrieving recorders. Please check if QlibRecorder is running or the name/id of the recorder is correct."
+                    )
+            else:
+                for rid in self.recorders:
+                    if self.recorders[rid].name == recorder_name:
+                        return self.recorders[rid]
+                if create:
+                    self.recorders = self.list_recorders()
+                    logger.warning(f"No valid recorder found. Create a new recorder with name {recorder_name}.")
+                    recorder = self.create_recorder()
+                    recorder.name = recorder_name
+                    recorder.start_run()
+                    return recorder
+                else:
+                    raise Exception(
+                        "Something went wrong when retrieving experiments. Please check if QlibRecorder is running or the name/id of the experiment is correct."
+                    )
+
+    def list_recorders(self):
+        client = mlflow.tracking.MlflowClient(tracking_uri=self._uri)
+        runs = client.list_run_infos(self.id)[::-1]
+        recorders = dict()
+        self._total_recorders = len(runs)
+        for i in range(len(runs)):
+            rid = runs[i].run_id
+            status = runs[i].status
+            start_time = runs[i].start_time
+            end_time = runs[i].end_time
+            recorder = MLflowRecorder(f"Recorder_{i+1}", self.id, self._uri)
+            recorder.id = rid
+            recorder.status = status
+            recorder.start_time = (
+                datetime.fromtimestamp(float(start_time) / 1000.0).strftime("%Y-%m-%d %H:%M:%S")
+                if start_time is not None
+                else None
+            )
+            recorder.end_time = (
+                datetime.fromtimestamp(float(end_time) / 1000.0).strftime("%Y-%m-%d %H:%M:%S")
+                if end_time is not None
+                else None
+            )
+            recorder._uri = self._uri
+            recorders[rid] = recorder
+
+        return recorders
diff --git a/qlib/workflow/expm.py b/qlib/workflow/expm.py
index f597d4a96..ebf6aeb7f 100644
--- a/qlib/workflow/expm.py
+++ b/qlib/workflow/expm.py
@@ -18,8 +18,9 @@ class ExpManager:
     (The link: https://mlflow.org/docs/latest/python_api/mlflow.html)
     """
 
-    def __init__(self):
-        self.uri = None
+    def __init__(self, uri, default_exp_name):
+        self.uri = uri
+        self.default_exp_name = default_exp_name
         self.active_experiment = None  # only one experiment can running each time
         self.experiments = dict()  # store the experiment name --> Experiment object
 
@@ -39,6 +40,7 @@ class ExpManager:
             controls whether run is nested in parent run.
 
         Returns
+        -------
         An active recorder.
         """
         raise NotImplementedError(f"Please implement the `start_exp` method.")
@@ -112,7 +114,7 @@ class ExpManager:
         """
         raise NotImplementedError(f"Please implement the `get_exp` method.")
 
-    def delete_exp(self, experiment_id):
+    def delete_exp(self, experiment_id=None, experiment_name=None):
         """
         Delete an experiment.
 
@@ -120,41 +122,51 @@ class ExpManager:
         ----------
         experiment_id  : str
             the experiment id.
+        experiment_name  : str
+            the experiment name.
         """
-        raise NotImplementedError(f"Please implement the `create_exp` method.")
+        raise NotImplementedError(f"Please implement the `delete_exp` method.")
 
     def get_uri(self):
         """
         Get the default tracking URI or current URI.
 
-        Parameters
-        ----------
-
         Returns
         -------
         The tracking URI string.
         """
         return self.uri
 
+    def list_experiments(self):
+        """
+        List all the existing experiments.
+
+        Returns
+        -------
+        A dictionary (name -> experiment) of experiments information that being stored.
+        """
+        raise NotImplementedError(f"Please implement the `list_experiments` method.")
+
 
 class MLflowExpManager(ExpManager):
     """
     Use mlflow to implement ExpManager.
     """
 
-    def __init__(self):
-        super(MLflowExpManager, self).__init__()
-        self.uri = None
+    def __init__(self, uri, default_exp_name):
+        super(MLflowExpManager, self).__init__(uri, default_exp_name)
+        self._total_exps = 0
+        # get all the exps
+        self.experiments = self.list_experiments()
 
     def start_exp(self, experiment_name=None, uri=None):
         # create experiment
         experiment = self.create_exp(experiment_name, uri)
         # set up active experiment
         self.active_experiment = experiment
-        # store the experiment
-        self.experiments[experiment_name] = experiment
         # start the experiment
         self.active_experiment.start()
+        self._total_exps += 1  # update exp num
 
         return self.active_experiment
 
@@ -162,10 +174,9 @@ class MLflowExpManager(ExpManager):
         if self.active_experiment is not None:
             self.active_experiment.end(status)
             self.active_experiment = None
+            self._total_exps -= 1
 
     def create_exp(self, experiment_name=None, uri=None):
-        # init experiment
-        experiment = MLflowExperiment()
         # set the tracking uri
         if uri is None:
             logger.info(
@@ -176,15 +187,19 @@ class MLflowExpManager(ExpManager):
         mlflow.set_tracking_uri(self.uri)
         # start the experiment
         if experiment_name is None:
-            logger.info("No experiment name provided. The default experiment name is set as `experiment`.")
-            experiment_id = mlflow.create_experiment("experiment")
+            logger.info(
+                f"No experiment name provided. The default experiment name is set as `{self.default_exp_name}`."
+            )
+            experiment_id = mlflow.create_experiment(self.default_exp_name)
             # set the active experiment
-            mlflow.set_experiment("experiment")
-            experiment_name = "experiment"
+            mlflow.set_experiment(self.default_exp_name)
+            experiment_name = self.default_exp_name
         else:
             if experiment_name not in self.experiments:
                 if mlflow.get_experiment_by_name(experiment_name) is not None:
-                    logger.info("The experiment has already been created before. Try to resume the experiment...")
+                    logger.info(
+                        "The experiment has already been created before. Try to resume the experiment with a new recorder..."
+                    )
                     experiment_id = mlflow.get_experiment_by_name(experiment_name).experiment_id
                 else:
                     experiment_id = mlflow.create_experiment(experiment_name)
@@ -193,9 +208,11 @@ class MLflowExpManager(ExpManager):
                 experiment = self.experiments[experiment_name]
         # set the active experiment
         mlflow.set_experiment(experiment_name)
-        # set up experiment
-        experiment.id = experiment_id
-        experiment.name = experiment_name
+        # init experiment
+        experiment = MLflowExperiment(experiment_id, experiment_name, self.uri)
+        experiment._default_name = self.default_exp_name
+        # store the experiment
+        self.experiments[experiment_name] = experiment
 
         return experiment
 
@@ -206,19 +223,73 @@ class MLflowExpManager(ExpManager):
         order_by = kwargs.get("order_by")
         return mlflow.search_runs(experiment_ids, filter_string, run_view_type, max_results, order_by)
 
-    def get_exp(self, experiment_id=None, experiment_name=None):
-        if experiment_name is not None:
-            return self.experiments[experiment_name]
-        elif experiment_id is not None:
-            for name in self.experiments:
-                if self.experiments[name].id == experiment_id:
-                    return self.experiments[name]
-        elif self.active_experiment is None:
-            raise Exception("No valid active experiment exists. Please make sure experiment manager is running.")
+    def get_exp(self, experiment_id=None, experiment_name=None, create=True):
+        if experiment_id is None and experiment_name is None:
+            if self.active_experiment:
+                return self.active_experiment
+            else:
+                if create:
+                    logger.warning("QlibRecorder is not running. Use the Default experiment for further process.")
+                    return self.start_exp()
+                else:
+                    raise Exception(
+                        "Something went wrong when retrieving experiments. Please check if QlibRecorder is running or the name/id of the experiment is correct."
+                    )
         else:
-            logger.info("No experiment id or name is given. Return the current active experiment.")
-            return self.active_experiment
+            if experiment_name is not None:
+                if experiment_name in self.experiments:
+                    return self.experiments[experiment_name]
+                else:
+                    if create:
+                        logger.warning(
+                            f"No valid experiment found. Create experiment with name {experiment_name} for further process."
+                        )
+                        return self.start_exp(experiment_name)
+                    else:
+                        raise Exception(
+                            "Something went wrong when retrieving experiments. Please check if QlibRecorder is running or the name/id of the experiment is correct."
+                        )
+            else:
+                for name in self.experiments:
+                    if self.experiments[name].id == experiment_id:
+                        return self.experiments[name]
+                if create:
+                    logger.warning(f"No valid experiment found. Use the Default experiment for further process.")
+                    return self.start_exp()
+                else:
+                    raise Exception(
+                        "Something went wrong when retrieving experiments. Please check if QlibRecorder is running or the name/id of the experiment is correct."
+                    )
 
-    def delete_exp(self, experiment_id):
-        mlflow.delete_experiment(experiment_id)
-        self.experiments = {key: val for key, val in self.experiments.items() if val.id != experiment_id}
+    def delete_exp(self, experiment_id=None, experiment_name=None):
+        assert (
+            experiment_id is not None or experiment_name is not None
+        ), "Please input a valid experiment id or name before deleting."
+        try:
+            if experiment_id is not None:
+                mlflow.delete_experiment(experiment_id)
+                self.experiments = {key: val for key, val in self.experiments.items() if val.id != experiment_id}
+            else:
+                experiment_id = self.experiments[experiment_name].id
+                mlflow.delete_experiment(experiment_id)
+        except:
+            raise Exception(
+                "Something went wrong when deleting experiment. Please check if the name/id of the experiment is correct."
+            )
+
+    def list_experiments(self):
+        # retrieve all the existing experiments
+        client = mlflow.tracking.MlflowClient(tracking_uri=self.uri)
+        exps = client.list_experiments()
+        experiments = dict()
+        self._total_exps = len(exps)
+        for i in range(len(exps)):
+            eid = exps[i].experiment_id
+            ename = exps[i].name
+            experiment = MLflowExperiment(eid, ename, self.uri)
+            experiment.id = eid
+            experiment.name = ename
+            experiment._uri = self.uri
+            experiments[ename] = experiment
+
+        return experiments
diff --git a/qlib/workflow/recorder.py b/qlib/workflow/recorder.py
index 68ce5432b..1adaa3f8a 100644
--- a/qlib/workflow/recorder.py
+++ b/qlib/workflow/recorder.py
@@ -2,7 +2,7 @@
 # Licensed under the MIT License.
 
 import mlflow
-import shutil, os, pickle, tempfile, codecs
+import shutil, os, pickle, tempfile, codecs, datetime
 from pathlib import Path
 from ..utils.objm import FileManager
 
@@ -19,6 +19,8 @@ class Recorder:
         self.id = None
         self.name = name
         self.experiment_id = experiment_id
+        self.start_time = None
+        self.end_time = None
         self.status = "SCHEDULED"
 
     def __repr__(self):
@@ -34,7 +36,10 @@ class Recorder:
         output["id"] = self.id
         output["name"] = self.name
         output["experiment_id"] = self.experiment_id
+        output["start_time"] = self.start_time
+        output["end_time"] = self.end_time
         output["status"] = self.status
+        return output
 
     def set_recorder_name(self, rname):
         self.recorder_name = rname
@@ -78,9 +83,6 @@ class Recorder:
         Start running or resuming the Recorder. The return value can be used as a context manager within a `with` block;
         otherwise, you must call end_run() to terminate the current run. (See `ActiveRun` class in mlflow)
 
-        Parameters
-        ----------
-
         Returns
         -------
         An active running object (e.g. mlflow.ActiveRun object).
@@ -139,7 +141,7 @@ class Recorder:
 
     def list_artifacts(self, artifact_path=None):
         """
-        Delete some tags from a run.
+        List all the artifacts of a recorder.
 
         Parameters
         ----------
@@ -161,10 +163,13 @@ class MLflowRecorder(Recorder):
     use file manager to help maintain the objects in the project.
     """
 
-    def __init__(self, name, experiment_id):
+    def __init__(self, name, experiment_id, uri):
         super(MLflowRecorder, self).__init__(name, experiment_id)
-        self.fm = None
-        self.temp_dir = None
+        self._uri = uri
+        self.artifact_uri = None
+        # set up file manager for saving objects
+        self.temp_dir = tempfile.mkdtemp()
+        self.fm = FileManager(Path(self.temp_dir).absolute())
 
     def start_run(self):
         # start the run
@@ -172,19 +177,21 @@ class MLflowRecorder(Recorder):
         # save the run id and artifact_uri
         self.id = run.info.run_id
         self.artifact_uri = run.info.artifact_uri
-        self._uri = mlflow.get_tracking_uri()  # Fix!!! : this is not proper to have uri in recorder
-        # set up file manager for saving objects
-        self.temp_dir = tempfile.mkdtemp()
-        self.fm = FileManager(Path(self.temp_dir).absolute())
+        self.start_time = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
         self.status = "RUNNING"
+
         return run
 
     def end_run(self, status):
+        assert status in ["SCHEDULED", "RUNNING", "FINISHED", "FAILED"], f"The status type {status} is not supported."
         mlflow.end_run(status)
-        self.status = status
+        self.end_time = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+        if self.status is not "FINISHED":
+            self.status = status
         shutil.rmtree(self.temp_dir)
 
     def save_objects(self, data_name_list=None, local_path=None, artifact_path=None, **kwargs):
+        assert self._uri is not None, "Please start the experiment and recorder first before using recorder directly."
         client = mlflow.tracking.MlflowClient(tracking_uri=self._uri)
         if local_path is not None:
             client.log_artifacts(self.id, local_path, artifact_path)
@@ -200,6 +207,7 @@ class MLflowRecorder(Recorder):
             raise Exception("Please provide valid arguments in order to save object properly.")
 
     def load_object(self, name):
+        assert self._uri is not None, "Please start the experiment and recorder first before using recorder directly."
         client = mlflow.tracking.MlflowClient(tracking_uri=self._uri)
         path = client.download_artifacts(self.id, name)
         try:
@@ -235,12 +243,16 @@ class MLflowRecorder(Recorder):
         for count, key in enumerate(keys):
             mlflow.delete_tag(key)
 
-    def get_artifact_uri(self, artifact_path=None):
+    def get_artifact_uri(self):
         if self.artifact_uri is not None:
             return self.artifact_uri
-        return mlflow.get_artifact_uri(artifact_path)
+        else:
+            raise Exception(
+                "Please make sure the recorder has been created and started properly before getting artifact uri."
+            )
 
     def list_artifacts(self, artifact_path=None):
+        assert self._uri is not None, "Please start the experiment and recorder first before using recorder directly."
         client = mlflow.tracking.MlflowClient(tracking_uri=self._uri)
         artifacts = client.list_artifacts(self.id, artifact_path)
         return artifacts