diff --git a/tools/train.py b/tools/train.py
index fab10b6437cfe5ad30bcb49d7b1b884ba9665a79..c12cf005638ad8be8f8b8fce42e682fed2f29be7 100755
--- a/tools/train.py
+++ b/tools/train.py
@@ -89,8 +89,10 @@ def main(config, device, logger, vdl_writer):
     # load pretrain model
     pre_best_model_dict = init_model(config, model, logger, optimizer)
 
-    logger.info('train dataloader has {} iters, valid dataloader has {} iters'.
-                format(len(train_dataloader), len(valid_dataloader)))
+    logger.info('train dataloader has {} iters'.format(len(train_dataloader)))
+    if valid_dataloader is not None:
+        logger.info('valid dataloader has {} iters'.format(
+            len(valid_dataloader)))
     # start train
     program.train(config, train_dataloader, valid_dataloader, device, model,
                   loss_class, optimizer, lr_scheduler, post_process_class,