diff --git a/paddle/fluid/operators/listen_and_serv_op.cc b/paddle/fluid/operators/listen_and_serv_op.cc
index bf351a2f52019ef05d6ebb827d39a7668639d96b..3ee642dedb8ec30e9f0ef972067e8ac4fcbf3d6c 100644
--- a/paddle/fluid/operators/listen_and_serv_op.cc
+++ b/paddle/fluid/operators/listen_and_serv_op.cc
@@ -332,8 +332,7 @@ from send_op and send back variables to recv_op.
         "['param1@GRAD.block0:1', 'param2@GRAD.blockn:2'] "
         "a map from grad name to it's optimize block id")
         .SetDefault({});
-    AddAttr<bool>("sync_mode", "if works at sync_mode or not")
-        .SetDefault(false);
+    AddAttr<bool>("sync_mode", "if works at sync_mode or not").SetDefault(true);
     AddAttr<framework::BlockDesc *>(kOptimizeBlock,
                                     "BlockID to run on server side.");
     AddAttr<framework::BlockDesc *>(kPrefetchBlock,