diff --git a/src/components/ruler.vue b/src/components/ruler.vue
index 3c5e244..aad5e4e 100644
--- a/src/components/ruler.vue
+++ b/src/components/ruler.vue
@@ -129,6 +129,8 @@ watch(() => props.dotIndex, (newVal, oldVal) => {
   }
   if (props.dotIndex >= 0) {
     getLineData('head', `dot${props.dotIndex + 1}`)
+  } else {
+    zoomScale(props.boxPos.y, 0)
   }
 })
 const getDistanceAndZoom = () => {