Abstract: Electron beam brazing of Nb-1Zr alloy to 304 stainless steel were investigated.It was found that two intermetallic compound layers were formed at brazing interface between stainless steel weld and Nb-1Zr alloy.The reaction layerⅠ on Nb-1Zr alloy side was loose organization formed of the Fe₂Nb,while reaction layer Ⅱon stainless steel weld was formed pillar crystal which was composed of laminated Fe₂Nb and Fe-Cr.The reaction layerⅠ brought on frailty of joint and crack in welding.Thickness of reaction layerⅠ related to electron beam focus offset,and caused changes in joint strength over 100 MPa.It was not obvious in this experiment that the electron beam current and welding speed caused changes of joint characteristics.