Abstract: The effect of repeated repair welding on the mechanical properties of electron beam welded joint of 30CrMnSiNi2A ultra-high strength steel was studied.The feasibility of electron beam repair welding technology in repairing weld was studied through the delamination tensile test and impact test of weld joints with different repair times.The experimental results show that the residual angular deformation of the test plate increases monotonically with the increase of the time of repair welding.The angular deformation after one, two and three times of repair welding is about 2.1°, 4.0° and 5.5°, respectively.The tensile strength of the joint is little affected by multiple times of repair welding, and the strength variation range is less than 1.5% under different repair welding times.With the increase of the time of repair welding, the overall plasticity of the joint decreases, and the impact toughness of the joint monotonically decreases.The results of the paper have guiding significance for the welding production of 30CrMnSiNi2A ultra-high strength steel structure.