Clamp capable of controlling extension and retraction of positioning pin

The utility model discloses a clamp capable of controlling a positioning pin to stretch out and draw back, and particularly relates to the technical field of clamps, the clamp comprises a plurality of clamp main bodies, and clamping mechanisms are arranged in the clamp main bodies; the clamping mechanism comprises a plurality of oil cylinders, the oil cylinders are arranged at the bottom of the clamp body respectively, pistons are arranged in the oil cylinders, the outer walls of the pistons make contact with the inner walls of the oil cylinders, positioning pins are arranged at the top ends of the pistons, and the positioning pins are arranged at the bottom of the clamp body and extend into the clamp body. And a screw is arranged between the positioning pin and the piston. According to the utility model, the size of the positioning pin corresponds to that of the positioning hole; the positioning pin is connected with the piston through the screw, the piston moves up and down in the oil cylinder to drive the