diff --git a/funasr/auto/auto_model.py b/funasr/auto/auto_model.py
index 9272f62bf..7db1eb606 100644
--- a/funasr/auto/auto_model.py
+++ b/funasr/auto/auto_model.py
@@ -330,6 +330,8 @@ class AutoModel:
 
         if run_mode == "extract_token" and hasattr(model, "writer"):
             model.writer.close()
+            if hasattr(model, "len_writer"):
+                model.len_writer.close()
 
         if pbar:
             # pbar.update(1)
diff --git a/funasr/models/sense_voice/model_small.py b/funasr/models/sense_voice/model_small.py
index 0d27b4d25..91d4a754f 100644
--- a/funasr/models/sense_voice/model_small.py
+++ b/funasr/models/sense_voice/model_small.py
@@ -2050,16 +2050,19 @@ class SenseVoiceL(nn.Module):
 
         results.append(result_i)
 
-        ark_writer = None
+        ark_writer, len_writer = None, None
         if kwargs.get("output_dir") is not None:
             out_dir = kwargs.get("output_dir")
             os.makedirs(out_dir, exist_ok=True)
             if not hasattr(self, "writer"):
                 out_path = os.path.join(out_dir, f"enc_token")
                 self.writer = kaldiio.WriteHelper(f"ark,scp,f:{out_path}.ark,{out_path}.scp")
+                self.len_writer = open(out_path+"_len.txt", "wt")
             ark_writer = self.writer
+            len_writer = self.len_writer
         if ark_writer is not None:
             for k, v, l in zip(key, tokens.detach().cpu().numpy(), out_lens):
                 ark_writer(k, v[:l])
+                len_writer.write(f"{k}\t{l}\n")
 
         return results, meta_data