The electron beam welding has high energy density, and the advantages of small welding deformation, in the defense, automotive, shipbuilding, precision machinery and other industries has been widely applied. Traditional electron beam welding machine power supply system adopts the technology of the power frequency or medium frequency, high volume, low efficiency and poor stability of electron beam. Combining with the characteristics of electron beam welding power source and the existing shortcomings, I put forward a digital filament power control scheme based on STM32, and introduce the hardware and software implementation method in detail. Experiments show that it can realize soft-start and soft-down process, and also be quickly identified and promptly forbid the output when filament fracture, which realize the intellectualization of filament power supply.