diff --git a/qlib/data/data.py b/qlib/data/data.py
index 116827f23..1b1353ee4 100644
--- a/qlib/data/data.py
+++ b/qlib/data/data.py
@@ -536,7 +536,6 @@ class DatasetProvider(abc.ABC):
         """
         if len(fields) == 0:
             raise ValueError("fields cannot be empty")
-        fields = fields.copy()
         column_names = [str(f) for f in fields]
         return column_names