Abstract: The joint of FGH96/GH4169 dissimilar superalloys was obtained by changing rotation rate on Inertia Friction Welding machine and the welded joint temperature was measured. After welding,optical microscope,Scanning Electron Microscope（ SEM） and tensile testing machine were used to investigate the microstructures and mechanical properties of the joint. The results showed that the temperature around the interface nearly exceeds 1 100 ℃. The microstructure in the weld zone（ WZ） consists of refined and equiaxed grains and that in the thermos-mechanically affected zone（ TMAZ） consists of deformed grains. After wedding γ’and γ" partly soluted in TMAZ and practically in WZ. The sizes of the refined grains become larger with rotation rate being increased. Elemental diffusion exists on the interface and the diffusion become wider with the increased rotation rate. The results of tensile properties show that the tensile strength rises with the rotation rate.