Abstract: To solve the quest of realizing synchronization, alternation and random phase control between the master and slave output in the twin-wire pulsed MIG welding, the 32-bit STM32F103ZET6 is adopted in the STM32 based power supply system for integrative twin-wire pulsed MIG welding. Synchronization, alternation and random phase control between two output is realized by single STM32F103ZET6 chip, whose integrated pulse width modulation (PWM) module produces PWM signal for phase-shift full-bridge soft-switching control, so that PWM control for the master and slave inverter is fully obtained by software, with high frequency invert and low frequency wave-form modulation achieved. The results show that the proposed power supply system meets the requirement of the design, as stable and high-speed welding process with little splash is acquired and the weld seam formation is decent.