Abstract: Direct diffusion bonding between a TA17 near α- titanium alloy and an 0Cr18Ni9Ti stainless steel at constant temperature and pressure has been carried out in vacuum. Titanium alloy and stainless steel had been treated by surface mechanical atrrition treatment before diffusion bonding.The tensile strength was tested by using the hydraumatic universal testing machine. SEM observation and EDS determination were employed to investigate the structure of the joint and phases on the fracture.The result show that the inter-face-structure of titanium alloy/stainless steel joint have different layered structures on the bonding inter-face.The bonding interfaces are with the same forms of the interface-structure at the different temperature; Comparing with non-treated materials, the diffusion velocity of atoms around the interface was faster,bonding time was shorter and the joint strength was higher under self-nanocrystallization condition.