diff --git a/oneflow/core/operator/op_conf.proto b/oneflow/core/operator/op_conf.proto
index 2094467b5262df1b395cca743f71a9b90e4ac7f6..5d70bb51e1b4c16fab330f82462c4249c0882007 100644
--- a/oneflow/core/operator/op_conf.proto
+++ b/oneflow/core/operator/op_conf.proto
@@ -679,7 +679,7 @@ message OperatorConf {
   optional bool trainable = 3 [default = true];
   optional DeviceType device_type = 4 [default = kInvalidDevice];
   optional bool enable_cudnn = 5;
-  optional int64 cudnn_buf_limit_mbyte = 6 [default = 1024]; // 1GByte
+  optional int64 cudnn_buf_limit_mbyte = 6 [default = 4096]; // 4GByte
   oneof op_type {
     // system op
     DecodeOFRecordOpConf decode_ofrecord_conf = 101;