Abstract: The 93W/Ni/QSn4-3 joint was prepared by diffusion bonding at vacuum using pure nickel foil as interface layer. The microstructure and composition were characterized by SEM and EPMA. The tensile strength of joint was also measured. The test results show that Ni foil improves the tensile strength of 93W/Ni/QSn4-3 joint. The thickness of Ni interlayer becomes thiner obviously because of the diffusion layer between Ni element of Ni foil and W and additional elements of 93W alloy, as well as the gradient layer of Ni and Cu elements. Solution reactions between Ni element of Ni foil and Cu element of QSn4-3 alloy, W and additional elements of 93W alloy achieve the joint of 93W/Ni/QSn4-3, that is why tensile strength of 93W/Ni/QSn4-3 joint welded is improved.