diff --git a/ppocr/postprocess/rec_postprocess.py b/ppocr/postprocess/rec_postprocess.py
index f64ea1ce7a..8b00be2192 100644
--- a/ppocr/postprocess/rec_postprocess.py
+++ b/ppocr/postprocess/rec_postprocess.py
@@ -956,15 +956,19 @@ def __call__(self, preds, label=None, length=None, *args, **kwargs):
             net_out = paddle.to_tensor(net_out, dtype='float32')
         net_out = F.softmax(net_out, axis=1)
         for i in range(0, length.shape[0]):
-            preds_idx = net_out[int(length[:i].sum()):int(length[:i].sum(
-            ) + length[i])].topk(1)[1][:, 0].tolist()
+            if i == 0:
+                start_idx = 0
+                end_idx = int(length[i])
+            else:
+                start_idx = int(length[:i].sum())
+                end_idx = int(length[:i].sum() + length[i])
+            preds_idx = net_out[start_idx:end_idx].topk(1)[1][:, 0].tolist()
             preds_text = ''.join([
                 self.character[idx - 1]
                 if idx > 0 and idx <= len(self.character) else ''
                 for idx in preds_idx
             ])
-            preds_prob = net_out[int(length[:i].sum()):int(length[:i].sum(
-            ) + length[i])].topk(1)[0][:, 0]
+            preds_prob = net_out[start_idx:end_idx].topk(1)[0][:, 0]
             preds_prob = paddle.exp(
                 paddle.log(preds_prob).sum() / (preds_prob.shape[0] + 1e-6))
             text.append((preds_text, float(preds_prob)))