diff --git a/python/paddle/trainer/PyDataProvider2.py b/python/paddle/trainer/PyDataProvider2.py
index 5ca4bcbca6906ae044035a689045bd6181a3827d..7b56b4a30ec891cfe8e4fc1be3c2a8a03e4b95e5 100644
--- a/python/paddle/trainer/PyDataProvider2.py
+++ b/python/paddle/trainer/PyDataProvider2.py
@@ -322,7 +322,13 @@ def provider(input_types=None,
                     self.logger.warning('setting slots value is deprecated, '
                                         'please use input_types instead.')
                     self.slots = outter_kwargs['slots']
-                self.slots = input_types
+
+                if input_types is not None:
+                    self.slots = input_types
+
+                assert self.slots is not None, \
+                    "Data Provider's input_types must be set"
+
                 self.should_shuffle = should_shuffle
 
                 true_table = [1, 't', 'true', 'on']