diff --git a/paddlespeech/s2t/io/dataloader.py b/paddlespeech/s2t/io/dataloader.py
index 831830241dc77cc97977f5c4404acb98e7f09df5..735d29da257837bfd3072807b735e03bf437cefa 100644
--- a/paddlespeech/s2t/io/dataloader.py
+++ b/paddlespeech/s2t/io/dataloader.py
@@ -389,6 +389,7 @@ class DataLoaderFactory():
                 config['mini_batch_size'] = args.ngpu
                 config['subsampling_factor'] = 1
                 config['num_encs'] = 1
+                config['shortest_first'] = False
             elif mode == 'valid':
                 config['manifest'] = config.dev_manifest
                 config['train_mode'] = False