diff --git a/paddle/fluid/operators/controlflow/conditional_block_op.h b/paddle/fluid/operators/controlflow/conditional_block_op.h
index 6513bae839e9894ee2b342c5d61fcbf9191a4123..a44cff555f0a17113ed45407104d06514403e2bf 100644
--- a/paddle/fluid/operators/controlflow/conditional_block_op.h
+++ b/paddle/fluid/operators/controlflow/conditional_block_op.h
@@ -117,7 +117,8 @@ class ConditionalBlockOpProtoMaker : public framework::OpProtoAndCheckerMaker {
     AddAttr<std::vector<std::string>>(ConditionalOp::kSkipEagerDeletionVars,
                                       "Vars that would not be deleted when "
                                       "garbage collection strategy enables")
-        .SetDefault(std::vector<std::string>());
+        .SetDefault(std::vector<std::string>())
+        .AsExtra();
     AddComment(R"DOC(Conditional block operator
 
 If `is_scalar_condition` is True, the conditional variable (Cond) is a scalar,