The invention relates to a mechanical limiting device, which comprises a left mechanism and a right mechanism bilaterally symmetrical, screw rods, wedge blocks, cross arms and a bottom plate. Each ofthe left mechanism and the right mechanism comprises a cross arm, a screw rod and wedge blocks; the two wedge blocks are nested into two ends of each axially horizontal screw rod; one wedge block is fixedly connected onto the bottom plate under each screw rod; the other wedge block is in threaded connection onto each screw rod; each cross arm is arranged above the wedge blocks; a top surface of each wedge block is a plane inclined from an axial end part of each outer screw rod to the center; and a bottom surface of each cross arm is matched with the top surface of each wedge block. According to the mechanical limiting device provided by the invention, the stability of axial dimensions of batch products can be realized, the precision of the products can be controlled to be within 0.1mm without being affected by workpiece temperature, excircle size and forming pressure, and micro adjustment can be electrically controlled, so that the labor intensity and the human cost are greatly reduced.