The invention is concerned with forming mould and its method for rolling cross wedge rolling worm axis roughcast, belonging to metal plastic metal forming technology field. Set mould on the rolling cross wedge rolling and send the heated stick stuff into the cross wedge roller through feeding equipment. The upper mould and down mould with model cavity on their surface to the roller move to same direction and the heated metal round stick stuff moves to the different direction with the action of mould. This realizes continuous radial condensation and extending distortion along axis to form the each step including the shape of worm tooth. The part of spiral tooth shape of the worm axis roughcast is finished through the spiral groove tooth shape of the mould, and the part of step axis is finished through the wedge part of mould. The roller moves around to produce a roughcast of worm axis. The invention has high single machine productivity and availability with low cost, less machining process and excellent quality of production.