diff --git a/pkg/schedule/placement/rule.go b/pkg/schedule/placement/rule.go
index 75ccd509ee8..df498109589 100644
--- a/pkg/schedule/placement/rule.go
+++ b/pkg/schedule/placement/rule.go
@@ -89,8 +89,7 @@ func (r *Rule) String() string {
 
 // Clone returns a copy of Rule.
 func (r *Rule) Clone() *Rule {
-	var clone Rule
-	json.Unmarshal([]byte(r.String()), &clone)
+	clone := *r
 	clone.StartKey = append(r.StartKey[:0:0], r.StartKey...)
 	clone.EndKey = append(r.EndKey[:0:0], r.EndKey...)
 	return &clone