diff --git a/internal/core/cs/metrics.go b/internal/core/cs/metrics.go
index 01257f4f..169126d3 100644
--- a/internal/core/cs/metrics.go
+++ b/internal/core/cs/metrics.go
@@ -20,6 +20,9 @@ type TweetMetric struct {
 }
 
 func (m *TweetMetric) RankScore(motivationFactor int) int64 {
+	if m.DecayFactor == 0 {
+		return 0
+	}
 	return int64(m.IncentiveScore * motivationFactor / m.DecayFactor)
 }
 
diff --git a/internal/dao/jinzhu/metrics.go b/internal/dao/jinzhu/metrics.go
index c39886f4..f73fad5c 100644
--- a/internal/dao/jinzhu/metrics.go
+++ b/internal/dao/jinzhu/metrics.go
@@ -43,7 +43,7 @@ func (s *tweetMetricSrvA) UpdateTweetMetric(metric *cs.TweetMetric) error {
 }
 
 func (s *tweetMetricSrvA) AddTweetMetric(postId int64) (err error) {
-	_, err = (&dbr.PostMetric{PostId: postId}).Create(s.db)
+	_, err = (&dbr.PostMetric{PostId: postId, DecayFactor: 100}).Create(s.db)
 	return
 }
 
@@ -64,7 +64,7 @@ func (s *commentMetricSrvA) UpdateCommentMetric(metric *cs.CommentMetric) error
 }
 
 func (s *commentMetricSrvA) AddCommentMetric(commentId int64) (err error) {
-	_, err = (&dbr.CommentMetric{CommentId: commentId}).Create(s.db)
+	_, err = (&dbr.CommentMetric{CommentId: commentId, DecayFactor: 100}).Create(s.db)
 	return
 }