diff --git a/paddle/operators/lod_reset_op.h b/paddle/operators/lod_reset_op.h
index a4495b3e4986c555bf2a16487b4e1f306db76904..2bb916ccee80c83a02ea429fe95f5fafc86ccfa6 100644
--- a/paddle/operators/lod_reset_op.h
+++ b/paddle/operators/lod_reset_op.h
@@ -54,7 +54,7 @@ class LoDResetKernel : public framework::OpKernel<T> {
     }
 
     out->ShareDataWith(*in);
-
+    // cast level0 to size_t
     std::vector<size_t> ulevel0(level0.size(), 0);
     std::transform(level0.begin(), level0.end(), ulevel0.begin(),
                    [](int a) { return static_cast<size_t>(a); });