On the basis of researching domestic and foreign baling machines twisting wire device, a new kind of twisting wire device was described. The twisting wire devices mechanical structure, hydraulic system and the PLC control principle were introduced. Twisting wire device was the core of the automatic baling machine which was powered by hydraulic oil and controlled by PLC to fulfill the action of the twisting wire device. The twist wire device could tighten while moving forward, thus the defect of wire rod wring due to the screw thread head spining around was overcome and the independent escapement and crowded flat organization of the baling machine were saved. 