diff --git a/qlib/config.py b/qlib/config.py
index 16df27b95..31b34bacd 100644
--- a/qlib/config.py
+++ b/qlib/config.py
@@ -20,7 +20,7 @@ import multiprocessing
 
 class Config:
     def __init__(self, default_conf):
-        self.__dict__["_default_config"] = default_conf  # avoiding conflictions with __getattr__
+        self.__dict__["_default_config"] = copy.deepcopy(default_conf)  # avoiding conflictions with __getattr__
         self.reset()
 
     def __getitem__(self, key):