diff --git a/src/operators/multiclass_nms_op.cpp b/src/operators/multiclass_nms_op.cpp
index d29b84e56521ef98d8b3fbf000e5f6fba809fea3..9d6ffaf3a78c036beb3e1783930c68d08be0cc0e 100644
--- a/src/operators/multiclass_nms_op.cpp
+++ b/src/operators/multiclass_nms_op.cpp
@@ -32,7 +32,8 @@ void MultiClassNMSOp<Dtype, T>::InferShape() const {
     LOG(kLOG_ERROR) << "Predict bboxes must be equal";
   }
   // pre size, will change in Compute.
-  this->param_.Out()->Resize(framework::make_ddim({input_bboxes_dims[1], 6}));
+  this->param_.Out()->Resize(
+      framework::make_ddim({input_bboxes_dims[1], input_bboxes_dims[2] + 2}));
 }
 
 }  // namespace operators