Abstract: Vanadium alloy have been identified as leading candidate for fusion energy systems. To construct more effective and economic system, dissimilar materials joints between vanadium alloys and stainless steel were required. The high vacuum electron beam isolationwelding(EBIW) was used to joining vanadium alloy(V-5Cr-5Ti) to stainless-steel(HR-2) with the middle transition metal of Au. The effect of electron beam(EB) offset on the joint properties was analyzed. The results show that the penetrated crack forms in the joint without EB off-set(d=0), which directly leads to failure of the joint. And the metallurgical bonding joint can be achieved by minimizing the formation of intermetallic compounds with EB off-set(d=r). Au as filler material exhibits good isolation layer which helps to suppress the formation of V/Fe intermetallic compounds, improve the weld quality. The tensile strength of vanadium alloy/stainless-steel of EBIW joint is higher than 380 MPa. The weld seams have good top and back appearance, and there is no crack and porosity in the joints detected by X-ray inspection.