diff --git a/towhee/runtime/pipeline.py b/towhee/runtime/pipeline.py
index f0821cf8a..659a29de1 100644
--- a/towhee/runtime/pipeline.py
+++ b/towhee/runtime/pipeline.py
@@ -514,4 +514,4 @@ def _concat_dag(dag1, pipes):
 
     @staticmethod
     def _check_schema(schema):
-        return TupleForm(schema_data=schema).schema_data
+        return TupleForm(data=None, schema_data=schema).schema_data