Abstract: The joining of 30Cr3MoA structural steel to ZQSn10-2-3 tin bronze was realized by vacuum diffusion welding. The tensile strength of the joints at different processes were tested,and the microstructure of the joints was observed by scanning electron microscopy（ SEM） and energy dispersive X-ray spectroscopy（ EDS）. The results show that the quality of diffusion bonded joint is the best at 820 ℃. The strength of joint can be increased by increasing pressure and prolonging holding time. The tensile strength of joint can reach up to 294 MPa at 820 ℃/1 h/10 MPa process. The tensile specimens are all broken in tin bronze base metal. The weld seam is defect-free metallurgical bonding and the interdiffusion layer between Cu and Fe elements is about 3 μm in thickness.