Disclosed herein is an improved structure of automatic retractable dog leash safety switch device, which utilizes positioning rods on a positioning switch in conjunction with the design of positioning guide grooves formed to the inner surfaces of two half casings and corresponding to the positioning rods on the positioning switch, so as to change the positioning manner of the positioning switch. After the positioning switch is in place, the lower section of the switch is unable to move left and right as it is limited by a limit stop wall of a limit mounting hole, thereby significantly increasing the overall bearable tension of the positioning switch by more than 50%, minimizing the reaction force imposed on the positioning switch due to the ratchet stopping action, improving the design flaws of conventional positioning switches that the positioning rods are directly inserted thereon and the reaction force is generated after the ratchet on the reel stops the positioning switch, and improving the angling phenomenon generated to the positioning rods in the guide grooves or the problem of the positioning rods sliding left and right on the positioning switch because of long-term use, which results in uneven depths of the left and right positioning rods after being inserted into the guide grooves, making the press button of the positioning switch unable to be positioned and the positioning rods easily damaged. This invention can always utilize the positioning switch to adjust the pets leash to a proper length so that it will not trail on the ground and be tainted by dirt and soil, thereby effectively improving the practicality and safety of the positioning switch device structure.一種自動伸縮狗鏈安全開關裝置結構改良,其利用定位開關上的定位桿,配合定位導槽形成於兩半殼體內面,並對應定位開關上定位桿之設計,改變定位開關的定位方式,該定位開關定位後,開關下段受限於限位安裝孔之限位擋壁,無法左右移動,可大幅增加整個定位開關承受之拉力百分之五十以上,並將定位開關受棘齒擋止之反作用力降到最低,改良習用定位開關上直接插設定位桿設計缺點,及捲盤上棘齒擋止定位開關後產生反作用力,改善定位桿於導槽內產生折角現象,或因長久使用後,定位桿於定位開關上左右滑動,造成左右定位桿插入導槽的深度不平均,使定位開關之按鈕無法定位及定位桿容易損壞問題,本發明可隨時利用定位開關調整寵物繫帶長度,使繫
