diff --git a/convlab2/evaluator/multiwoz_eval.py b/convlab2/evaluator/multiwoz_eval.py
index 86c0ed7b1a9aa2667661c48cb7fc26a112fd364c..202e248f217cf7f42f281a398c5f45c32068299a 100755
--- a/convlab2/evaluator/multiwoz_eval.py
+++ b/convlab2/evaluator/multiwoz_eval.py
@@ -93,6 +93,7 @@ class MultiWozEvaluator(Evaluator):
         self.cur_domain = ''
         self.booked = self._init_dict_booked()
         self.booked_states = self._init_dict_booked()
+        self.successful_domains = []
 
     def add_sys_da(self, da_turn, belief_state):
         """add sys_da into array