diff --git a/src/store/actions/index.ts b/src/store/actions/index.ts
index bdfd612..327b45a 100644
--- a/src/store/actions/index.ts
+++ b/src/store/actions/index.ts
@@ -25,6 +25,7 @@ export class EditorAction {
   mapEditor: IMapEditor | null = null;
   store: IStore;
   id: string;
+  autoSaveTimer: number = -1;
 
   constructor(store: IStore) {
     this.store = store;
@@ -60,9 +61,7 @@ export class EditorAction {
       this._openProject(JSON.parse(cached));
     }
 
-    setInterval(() => {
-      this.saveTemp();
-    }, AutoCacheInterval);
+    this.autoSaveTimer = setTimeout(() => this.saveTemp(), AutoCacheInterval);
   }
 
   // ---------- public methods -------------
@@ -125,8 +124,10 @@ export class EditorAction {
   }
 
   async saveTemp() {
+    clearTimeout(this.autoSaveTimer);
     await setItem(this.id, JSON.stringify(this._getMapOptions()));
     message.success("暂存成功~");
+    this.autoSaveTimer = setTimeout(() => this.saveTemp(), AutoCacheInterval);
   }
 
   clearOverlays() {
@@ -209,6 +210,7 @@ export class EditorAction {
 
   private _bindActions() {
     this.saveGeoJSON = this.saveGeoJSON.bind(this);
+    this.saveTemp = this.saveTemp.bind(this);
     this.saveProject = this.saveProject.bind(this);
     this.openGeoJSON = this.openGeoJSON.bind(this);
     this.openProject = this.openProject.bind(this);
diff --git a/src/store/utils/getGeoJSON.ts b/src/store/utils/getGeoJSON.ts
index 91076ee..86f6f68 100644
--- a/src/store/utils/getGeoJSON.ts
+++ b/src/store/utils/getGeoJSON.ts
@@ -116,17 +116,17 @@ function getCirclePath(center: GeoJSON.Position, radius: number) {
   return path;
 }
 
-// todo: 转换并不是很准确, 需要好好研究一下.
 function getLngLatWithDistance(
   center: GeoJSON.Position,
   distance: number,
   direction: number
 ) {
-  distance /= EarthRadius;
+  distance /= EarthRadius * Math.PI * 2;
   const [lng, lat] = center;
+  // 差不多的数字...
   return [
-    lng + distance * Math.cos(direction),
-    lat + distance * Math.sin(direction),
+    lng + distance * 360 * Math.cos(direction),
+    lat + distance * 320 * Math.sin(direction),
   ];
 }