Abstract: This paper presents a full digital control system for pulsed gas metal arc welding inverter. The desirable control performance is achieved with the accurately controlled current waveform and high-speed stable arc-length adjustment.A PI regulator with variable parameters is adopted for flexible and accurate current-waveform control. In addition, a new arc-length control method is presented,and the higher adjustment performance is achieved within a wide range. The experimental results validate the system design, the stable and repeatable current waveforms are obtained, and the arc-length becomes robust against the variations of welding parameters.