The utility model relates to an accurate pneumatic centre gripping mechanical gripper for sheet metal class work piece. Including hand claw fixture, hand claw moving mechanism and profiling moving mechanism. Hand claw fixture includes a pair of platelike hand claw corresponding from top to bottom, controls a pair of profiling and the positioning mechanism that correspond, hand claw moving mechanism includes a sliding baseboard and an internal guide rail, profiling moving mechanism includes u -shaped frame, cylinder and a pair of outer guide. The cylinder passes through u -shaped frame and drives a pair of profiling reciprocating motion, the clamp that removes a pair of platelike hand claw of in -process control tight with loosen, simultaneously, adversary's claw passes through the reciprocating motion that sliding baseboard realized following an internal guide rail. The utility model has the advantages of reasonable design, can realize through a cylinder that mechanical gripper moving as a whole and mechanical gripper go up the lower plate and press from both sides and tightly wait whole the action with unclamping.