diff --git a/python/paddle/trainer_config_helpers/layers.py b/python/paddle/trainer_config_helpers/layers.py
index ed93fb72e0..cac71539f5 100755
--- a/python/paddle/trainer_config_helpers/layers.py
+++ b/python/paddle/trainer_config_helpers/layers.py
@@ -1023,6 +1023,7 @@ def cross_channel_norm_layer(input, name=None, param_attr=None):
     :type param_attr: ParameterAttribute
     :return: LayerOutput
     """
+    assert input.num_filters is not None
     Layer(
         name=name,
         type=LayerType.NORM_LAYER,