The invention discloses a main drive gear of a numerical control right-angle plate shearing machine in the field of plate shearing machine, which comprises a machine body; an upper knife rest is connected with the machine body through an uprightly arranged guide rail sliding block mechanism; a servo motor and a bearing pedestal are arranged on the machine body; an output shaft of the servo motor is connected with the upper end of a hollow support shaft through a synchronous belt and a synchronous belt wheel; the support shaft is mounted on the bearing pedestal through a bearing; the support shaft is connected with a ball-screw kinematic pair; a nut in the ball-screw kinematic pair is fixed at the lower end of the support shaft; the upper end of a screw rod in the ball-screw kinematic pairstretches into the hollow support shaft; the lower end of the screw rod in the ball-screw kinematic pair is fixedly connected with the shaft end of a ball rod; the ball part at the lower end of the ball rod is correspondingly arranged in a ball seat; a ball gland bush for fixing the ball rod is connected with the ball seat; and the ball seat is fixedly connected with the upper knife rest. The main drive gear of the numerical control right-angle plate shearing machine has the advantages of energy saving, quick processing, and high processing precision, and can be used for the right-angle shearing processing of various plate materials.