diff --git a/qlib/rl/utils/finite_env.py b/qlib/rl/utils/finite_env.py
index 28e2c80ba..d3dbfa1f7 100644
--- a/qlib/rl/utils/finite_env.py
+++ b/qlib/rl/utils/finite_env.py
@@ -56,11 +56,10 @@ def fill_invalid(obj: int | float | bool | np.ndarray | dict | list | tuple) ->
 
 
 def is_invalid(arr: int | float | bool | np.ndarray | dict | list | tuple) -> bool:
-    if hasattr(arr, "dtype"):
-        dtype = getattr(arr, "dtype")
-        if np.issubdtype(dtype, np.floating):
+    if isinstance(arr, np.ndarray):
+        if np.issubdtype(arr.dtype, np.floating):
             return np.isnan(arr).all()
-        return (np.iinfo(dtype).max == arr).all()
+        return (np.iinfo(arr.dtype).max == arr).all()
     if isinstance(arr, dict):
         return all(is_invalid(o) for o in arr.values())
     if isinstance(arr, (list, tuple)):