The reasonable design of forced air cooling and heat dissipation for inverter welding machine is conducive to improving the reliability of the whole machine and prolonging the service life of the equipment. Combining with an example,the theoretical calculation method of IGBT module heat dissipation design of inverter welding machine under forced air cooling is put forward, and the simulation analysis and test verification are carried out on the calculated results. The results show that this calculation method can meet the design requirements,and can provide technical reference for heat dissipation design of high-power products such as electric welding machine.