Abstract: In order to suppress the harmonic interference between inverter twin wire arc welding power source and power grid and improve the working stability of inverter power source, a main circuit of inverter arc welding power source combined with soft switch and LCL filter is proposed to improve the electromagnetic compatibility of the system. By using soft switching inverter topology, the switching stress of power devices is reduced, the harmonic amplitude is suppressed, and the stability of inverter power supply is improved. By designing a three-phase LCL filter at the input side of the power supply, the influence of grid harmonics on the inverter power supply is reduced, and the harmonic interference of power device switches on the grid is reduced. Aiming at the resonance problem of LCL filter, the method of filter capacitor series resistance is adopted to effectively suppress the resonance and ensure the stable operation of the system. The theoretical analysis and software simulation of ZVZCS soft switch and LCL filter are carried out. The results show that the working stability of inverter power supply is improved and the harmonic interference to power grid is reduced by combining LCL filter with soft switch power supply. The electromagnetic compatibility of the system is improved by this design.