diff --git a/paddle/fluid/operators/lookup_table_op.cc b/paddle/fluid/operators/lookup_table_op.cc
index 5971f0ddd4e9cd773854b8f0faf840960bfbe10f..d7f6cd5ab0acd2b677a3e5bd51bbcffe82eb1e50 100644
--- a/paddle/fluid/operators/lookup_table_op.cc
+++ b/paddle/fluid/operators/lookup_table_op.cc
@@ -81,6 +81,8 @@ class LookupTableOpMaker : public framework::OpProtoAndCheckerMaker {
                      "Otherwise the given value indicates padding the output "
                      "with zeros whenever lookup encounters it in Ids.")
         .SetDefault(kNoPadding);
+    // NOTE(minqiyang): grad_inplace is an temporal attribute,
+    // please do NOT set this attribute in python layer.
     AddAttr<bool>("grad_inplace",
                   "(boolean, default false) "
                   "If the grad op reuse the input's variable.")