diff --git a/PutTowerPosition/cmd.cs b/PutTowerPosition/cmd.cs
index 876bafb..da3db12 100644
--- a/PutTowerPosition/cmd.cs
+++ b/PutTowerPosition/cmd.cs
@@ -41,9 +41,21 @@ namespace PutTowerPosition
             public string towerName;
         }
 
+        struct Tower
+        {
+            public ObjectId point;
+            public ObjectId name;
+        }
+
+        private static List<Tower> latestTowerList = null;//记录最近一次加点的ID。
+
         [CommandMethod("ptp", CommandFlags.Session)]
         public static void PutTowerPositionCmd()
         {
+            if (latestTowerList == null)
+            {
+                latestTowerList = new List<Tower>();
+            }
             Gui gui = new Gui();
             gui.Show();
         }
@@ -74,7 +86,19 @@ namespace PutTowerPosition
                     acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
 
                                                     OpenMode.ForWrite) as BlockTableRecord;
-
+                    //先删除最后一次的塔位
+                    if (latestTowerList != null)
+                    { 
+                        foreach(Tower tower in latestTowerList)
+                        {
+                            DBText latestTowerName = acTrans.GetObject(tower.name, OpenMode.ForWrite) as DBText;
+                            DBPoint latestTowerPoint = acTrans.GetObject(tower.point, OpenMode.ForWrite) as DBPoint;
+                            latestTowerName.Erase();
+                            latestTowerPoint.Erase();
+                        }
+                        latestTowerList.Clear();
+                        
+                    }
                     Position[] cordinationList = calTowerXYPostion(cordDic, spanList);
                     foreach (Position point in cordinationList)
                     {
@@ -92,6 +116,10 @@ namespace PutTowerPosition
                         dbTowerName.Height = 40;
                         acBlkTblRec.AppendEntity(dbTowerName);
                         acTrans.AddNewlyCreatedDBObject(dbTowerName,true);
+                        Tower latestTower;
+                        latestTower.name = dbTowerName.ObjectId;
+                        latestTower.point = dbPoint.ObjectId;
+                        latestTowerList.Add(latestTower);
                     }
                     acTrans.Commit();
             }