Due to the differences in physical property， low density niobium alloy and niobium-hafnium alloy were easy to produce welding defects when they were welded by conventional electron beam method. To further explore the feasibility of welding between low density niobium alloy and niobium-hafnium alloy， properties of the welded joint were numerical simulated and experimental studied. Firstly， the finite element model of dissimilar materials was established， and the temperature field of the joint was analyzed. Then， the experimental study was carried out by electron beam welding， and the macroscopic morphology， mechanical properties， microstructure and element distribution of the joint were analyzed. The results show that the joint of low density niobium-hafnium alloy and niobium-hafnium alloy without cracks， pores and has good tensile strength can be obtained by electron beam welding with niobium-hafnium alloy side offset.