Abstract: The welding current control for inverter source is the key that meets requirements of varied welding processes and ensures the operation stability and reliability.A switch control mode which controlled pulse width of inverter source was proposed in this paper.The authors analyzed the fundamental and the static and dynamic property of the system theoretically,and simplified control mode of PID and fuzzy algorithms.This method was used in the system controlled by single chip microcomputer for inverter source of manual arc welding and TIG welding.The experiments showed that the rapid regulation without overshoot of welding current could be realized in the whole range of arc load.It met requirements of varied welding processes and ensured the operating stability and reliability of inverter source.