Abstract: The functions of the output filter inductor in inverter CO₂ gas shielded arc welding machine is studied.Based on theory analysis,the method that electronic inductor takes the place of the traditional inductor inductor is given out.Demonstrated by calculation and related experiments,the paper puts out conditions that limit the minimization of filter inductor.the results indicate that the functions of the filter inductor in inverter are different form those in traditional welding machine.Excellent dynamic characteristics can be achieved by using electronic inductor.the filter inductor has little effect on short circuit current or arc energy,but it is important for inhibiting the over current at the beginning of the short circuit which will lead to big spatter.Small inductor will also result in arc going out at the beginning of the short circuit or arc burning.