In the design of pulse welding digital control system,in view of the different requirements of the control system during the control of the base current and peak current,as well as the possible instantaneous transition of the digital PI operation results when the base value and peak value are switched instantaneously,this paper designs a digital double PI algorithm to control the base value and peak value respectively,and compares it with the case that only one PI regulator is used to control the base value and peak value. It is found that the control effect of double PI algorithm is good and the system is stable.According to the characteristics of variable speed integral PI control, the transition time of the pulse peak after the arc striking can be reduced by using the double PI algorithm. The process test shows that this method can effectively improve the primary arc striking rate.