diff --git a/tests/benchmark/milvus_benchmark/client.py b/tests/benchmark/milvus_benchmark/client.py
index 48deb2f08d..de217374bf 100644
--- a/tests/benchmark/milvus_benchmark/client.py
+++ b/tests/benchmark/milvus_benchmark/client.py
@@ -224,6 +224,7 @@ class MilvusClient(object):
 
     @time_wrapper
     def delete(self, ids, collection_name=None):
+        # delete entity by id
         tmp_collection_name = self._collection_name if collection_name is None else collection_name
         self._milvus.delete_entity_by_id(tmp_collection_name, ids)