diff --git a/ppdet/engine/trainer.py b/ppdet/engine/trainer.py
index 5aaabcacb4683ad529760d2f60aabaf01133c90a..2ae67bd91261e6bfafef63e82ff66c2798524ce4 100644
--- a/ppdet/engine/trainer.py
+++ b/ppdet/engine/trainer.py
@@ -339,7 +339,8 @@ class Trainer(object):
         assert self.mode == 'train', "Model not in 'train' mode"
         Init_mark = False
         if validate:
-            self.cfg.EvalDataset = create("EvalDataset")()
+            self.cfg['EvalDataset'] = self.cfg.EvalDataset = create(
+                "EvalDataset")()
 
         model = self.model
         if self.cfg.get('fleet', False):