Abstract: Electron beam welding was used to join alumi-num alloy 5A02 to stainless steel 0Cr18Ni9.Weld appearance,microstructure,mechanical properties and fracture characteristics were studied.The result showed that a lot of brittle Fe-Al inter-metallic compounds were formed in the joint welded by electron beam at the center between aluminum alloy 5A02 and stainless steel 0Cr18Ni9 and the base metals were not joined effectively.The formation of non-centered joints was good in general,and the base metals were joined in the form of fusion-brazing.There is a compounds layer about 1.5 μm in thickness on the interface of the joint,and the XRD analysis showed that it is comprised of FeAl,FeAl₃ and FeAl₆.The highest tensile strength of the joint was 136 MPa,reaches 62.7% of the aluminum alloy.The frac-ture showed a mixed brittle-ductile feature,and the fracture oc-cured in the compound layer and the aluminum weld near the compound layer.