The effects of different bonding temperatures on the microstructure and mechanical properties of TC11 alloy diffusion bonded joints were investigated and compared with the original base metal. The experimental results show that the optimal parameter for direct diffusion bonding of TC11 alloy was 900 ℃/30 min/60 min. There are no holes at the interface of the diffusion bonded joint, and the tensile strength of the joint was close to that of the original TC11alloy base metal. In addition, the plasticity of TC11 alloy diffusion bonded joint was better than that of the original base metal. High cycle fatigue properties tests were performed at room temperature for the original TC11 alloy base metal and the diffusion bonded joints under optimal process parameter. Compared with the original TC11 alloy base metal, the fatigue property of the direct diffusion bonding of the TC11 alloy was reduced, and all the diffusion bonded joint fractures occur at the diffusion bonded interface. By observing the microstructural characteristics of the fatigue fracture and interface, it is concluded that the difference in the crystal orientation of the base metal on both sides of the interface of the diffusion joint caused fatigue crack initiation, which is the main reason for reducing the fatigue property of the diffusion bonded joint.