Abstract: According to characteristics of thin strip cold rolling product line, the total configuration and control system of special flash butt welding machine in thin strip cold rolling was designed. The control system includes running-in speed control of movable clamp, position control of movable damp and upset control. Control of running-in speed of moveable clamp consists of velocity function, sensitivity function and welding current function.According to the different flash mode, moveable clamp position function can be calculated.Position of moveable clamp is controlled by position function of moveable clamp.Upset phase is controlled by position of moveable clamp in the welding.