Telescopic supporting leg for lorry-mounted crane

The utility model discloses a telescopic supporting leg for a lorry-mounted crane, and relates to the technical field of cranes. One end of the main beam is connected with the crane body; the other end of the main cross beam is connected with a supporting leg, the supporting leg comprises a vertical oil cylinder and a supporting leg base, and the supporting leg base is fixedly connected with the bottom of the vertical oil cylinder; a supporting sliding rail is arranged on a fixing part of the vertical oil cylinder, a supporting block is connected to the supporting sliding rail in a sliding mode, the vertical oil cylinder is sleeved with a lifting sleeve, and the inner side face of the lifting sleeve is fixedly connected with the supporting block. The main cross beam drives the supporting leg to move and lift, after the supporting leg base abuts against the ground, the supporting sliding rail runs to drive the lifting sleeve to descend through the supporting block, in the process, when the driving motor runs,