diff --git a/mindspore-lite/schema/ops.fbs b/mindspore-lite/schema/ops.fbs
index 27c27c86c203f5949a1ef8989e153570af59669d..645e529be479d1551edbfc0da10d1d7cf4219c02 100644
--- a/mindspore-lite/schema/ops.fbs
+++ b/mindspore-lite/schema/ops.fbs
@@ -304,7 +304,7 @@ table ArgMaxFusion {
 
 table ArgMinFusion {
     axis: long;
-    top_k: long;
+    top_k: long = 1;
     keep_dims: bool;
     out_max_value: bool;
 }