Abstract: According to characteristic of cold rolling and pickling line,this article presents total configuration and control system of special flash butt welding machine in cold rolling and pickling line.The power system of special flash butt welding is analyzed,the mathematics model is built,its main circuit adopts single phase AC voltage controller.The flash process includes the former and the later.In the flash stage,output voltage is controlled by transformer tap and thyristor control angle is π.In the upset stage,output voltage is controlled by thyristor control angle.Running-in speed of upset hydraulic system is controlled by error bet ween upset hydraulic cylinder actual value and the flash curve.Experiments showed that the flash welding machine met the requirements of strip billets welding.