diff --git a/oneflow/core/kernel/model_diff_accumulate_kernel.cpp b/oneflow/core/kernel/model_diff_accumulate_kernel.cpp
index 9c2d2a5835754d801ebaba142c90cc8cc1151d3b..80f913b4f2713ec069d16fbdfa5dd5a962d01b06 100644
--- a/oneflow/core/kernel/model_diff_accumulate_kernel.cpp
+++ b/oneflow/core/kernel/model_diff_accumulate_kernel.cpp
@@ -9,8 +9,7 @@ void MdDiffAccKernel<device_type, FloatingPointType>::Forward(
   Blob* in_blob = BnInOp2BlobPtr("model_diff");
   Blob* out_blob = BnInOp2BlobPtr("model_diff_acc");
   KernelUtil<device_type, FloatingPointType>::BlasAxpy(
-      ctx, in_blob->shape().elem_cnt() * sizeof(FloatingPointType),
-      static_cast<FloatingPointType>(1.0),
+      ctx, in_blob->shape().elem_cnt(), static_cast<FloatingPointType>(1.0),
       static_cast<const FloatingPointType*>(in_blob->dptr()), 1,
       static_cast<FloatingPointType*>(out_blob->mut_dptr()), 1);
 }