Positioning pin telescopic device

The utility model provides a positioning pin telescopic device which comprises an air cylinder, a lifting type impact rod fixedly connected with the air cylinder, a telescopic rod connected with the impact rod and a positioning pin installed at the top end of the telescopic rod, and the bottom end and the top end of the impact rod are connected with the air cylinder and the telescopic rod respectively. The impact rod is provided with an upper convex part, a lower convex part and a rod body connected with the upper convex part and the lower convex part, the upper convex part and the rod body are clamped in the telescopic rod and can drive the telescopic rod downwards when the impact rod descends, and the lower convex part is exposed out of the telescopic rod and can push the telescopic rod upwards when the impact rod ascends. Compared with the prior art, the telescopic rod is driven by the impact rod to do telescopic motion, so that the positioning pin is pushed to act on a workpiece or is driven to be separat