Abstract: For the electron beam welding of 5 mm thick 440C stainless steel, the effect of different scanning waveform on the weld formation and microstructure was studied. Based on the test results, the heat source model corresponding to different scanning waveforms was established, and the temperature field during electron beam welding at different scanning waveforms was analyzed. The results show that under the same welding parameters, the heat density of electron beam welding with triangle wave scanning is more concentrated, the surface fusion width is smaller, and the penetration weld is obtained. The heat of electron beam welding with circular wave scanning is dispersive, and non penetration weld is obtained. The grains of the electron beam weld with triangle wave scanning are finer and more uniform, and the proportion of long grains over 160μm is significantly lower than that of circular wave scanning. "Gauss surface heat source+cylinder heat source" model was established by Abaqus finite element software to simulate electron beam penetration welding structure, the model of "ellipsoid heat source+cone heat source" was established to simulate the non penetration electron beam welding, and the simulation results are in good agreement with the experimental results.