diff --git a/paddle/fluid/operators/detection/roi_perspective_transform_op.cc b/paddle/fluid/operators/detection/roi_perspective_transform_op.cc
index 4cc980b41b34894f9d915d4b325887548091c0eb..42c720e701fbabacf1280dec2f78d3f6b99dfea2 100644
--- a/paddle/fluid/operators/detection/roi_perspective_transform_op.cc
+++ b/paddle/fluid/operators/detection/roi_perspective_transform_op.cc
@@ -104,7 +104,6 @@ bool in_quad(T x, T y, T roi_x[], T roi_y[]) {
  * a31 = (dx3 * dy2 - dx2 * dy3) / (dx1 * dy2 - dx2 * dy1) / (w - 1)
  * a32 = (dx1 * dy3 - dx3 * dy1) / (dx1 * dy2 - dx2 * dy1) / (h - 1)
  * a33 = 1
- *
  */
 template <typename T>
 void get_transform_matrix(const int transformed_width,
@@ -260,8 +259,8 @@ class CPUROIPerspectiveTransformOpKernel : public framework::OpKernel<T> {
     roi2image.Resize({rois_num});
     int* roi2image_data = roi2image.mutable_data<int>(ctx.GetPlace());
     auto lod = rois->lod().back();
-    for (int i = 0; i < lod.size() - 1; ++i) {
-      for (int j = lod[i]; j < lod[i + 1]; ++j) {
+    for (size_t i = 0; i < lod.size() - 1; ++i) {
+      for (size_t j = lod[i]; j < lod[i + 1]; ++j) {
         roi2image_data[j] = i;
       }
     }
@@ -393,8 +392,8 @@ class CPUROIPerspectiveTransformGradOpKernel : public framework::OpKernel<T> {
     roi2image.Resize({rois_num});
     int* roi2image_data = roi2image.mutable_data<int>(ctx.GetPlace());
     auto lod = rois->lod().back();
-    for (int i = 0; i < lod.size() - 1; ++i) {
-      for (int j = lod[i]; j < lod[i + 1]; ++j) {
+    for (size_t i = 0; i < lod.size() - 1; ++i) {
+      for (size_t j = lod[i]; j < lod[i + 1]; ++j) {
         roi2image_data[j] = i;
       }
     }
@@ -404,7 +403,7 @@ class CPUROIPerspectiveTransformGradOpKernel : public framework::OpKernel<T> {
         for (int in_h = 0; in_h < in_height; ++in_h) {
           for (int in_w = 0; in_w < in_width; ++in_w) {
             T gradient = 0.0;
-            for (int roi_idx = lod[n]; roi_idx < lod[n + 1]; ++roi_idx) {
+            for (size_t roi_idx = lod[n]; roi_idx < lod[n + 1]; ++roi_idx) {
               const T* rois = rois_data + roi_idx * 8;
               T roi_x[4];
               T roi_y[4];
diff --git a/paddle/fluid/operators/detection/roi_perspective_transform_op.cu b/paddle/fluid/operators/detection/roi_perspective_transform_op.cu
index b683b7573db747bde5f57e530ec53760db099843..c82930cc4994c3854e60f40ae9909a90d82cbff6 100644
--- a/paddle/fluid/operators/detection/roi_perspective_transform_op.cu
+++ b/paddle/fluid/operators/detection/roi_perspective_transform_op.cu
@@ -345,8 +345,8 @@ class CUDAROIPerspectiveTransformOpKernel : public framework::OpKernel<T> {
     roi2image.Resize({rois_num});
     int* roi2image_data = roi2image.mutable_data<int>(platform::CPUPlace());
     auto lod = rois->lod().back();
-    for (int i = 0; i < lod.size() - 1; ++i) {
-      for (int j = lod[i]; j < lod[i + 1]; ++j) {
+    for (size_t i = 0; i < lod.size() - 1; ++i) {
+      for (size_t j = lod[i]; j < lod[i + 1]; ++j) {
         roi2image_data[j] = i;
       }
     }
@@ -432,7 +432,7 @@ __global__ void RoiTransformGradKernel(
 
     T gradient = 0.0;
     // Accumulate gradient over all RoIs that interpolated this element
-    for (int roi_idx = lod[n]; roi_idx < lod[n + 1]; ++roi_idx) {
+    for (size_t roi_idx = lod[n]; roi_idx < lod[n + 1]; ++roi_idx) {
       const T* rois = rois_data + roi_idx * 8;
       T roi_x[4];
       T roi_y[4];