Abstract: Aiming at the additive manufacturing problem of 6061 aluminum alloy, a 3D finite element model of 6061 aluminum alloy Selective Electron Beam Melting（SEBM） temperature field simulation was constructed by ANSYS. Considering the characteristics of the thermal properties of the material with temperature, the influence of electron beam power, scanning speed and preheating temperature on the size of the molten pool and the thermal history of the molten pool was studied by using a Gaussian surface heat source and moving on the powder bed, which provides a theoretical basis for the selection of the process parameters of additive manufacturing of 6061 aluminum alloy electron beam. The results show that the width and depth of the molten pool increase with the increase of the electron beam power and the preheating temperature, and decrease with the increase of scanning speed. When the input line energy is greater than 0.19 J/mm, the length of the melt pool decreases with the increase of the scanning speed, and when the line energy is less than 0.19 J/mm, the length of the melting pool increases with the increase of the scanning speed. Electron beam power is the main factor affecting the cooling rate; the temperature distribution of the powder layer of different scanning paths is different, and the different scanning paths of different powder layers are conducive to the processing quality of the entire part.