Abstract: With the increase of switching frequency, reducing stray inductance becomes one of the key factors in designing high frequency arc welding inverter. In order to meet the demand of DPS-500 of 50 kHz/20 kW, a laminated busbar was designed, which integrated DC link capacitor, soft start circuit, IGBT module and three-phase rectifier module. The numerical calculation of quasi-static electromagnetic field was carried out using ANSYS Q3D. Parasitic parameter matrices were extracted. The multi-port circuit model of the laminated busbar was built. The impedance vs frequency characteristic and the switching behavior of the laminated busbar was simulated and measured individually based on impedance resonance method and double pulse test method. Stray inductance of the laminated busbar was extracted by two different ways aforementioned. The results showed that the design was valid. The modeling accuracy of the laminated busbar was verified in frequency and temporal-domain by comparing results of simulation and experiment. Finally, the causes of errors was discussed.