Abstract: The electron beam welding of 20 mm 7A52 aluminum alloy plates was conducted.The welding parameters were determined by the method of multiple specimens and the mechanical properties of the joints were examined.The results showed that the satisfing weld appearance can be achieved when the accelerating voltage was 60 kV, electron beam current was 120 mA, focus current was 763 mA and welding speed was 800 mm/min.The ratio of depth to width obviously increased with the increase of electron beam current.Tiny alteration of focus current caused significant change in the weld shape.Fine and uniform grains occurred in the weld seam, and the fracture strength, weld hardness and impact toughness of the joint reached 87%, 61% and 95.4% of those of base metal, respectively.