Abstract: The influence of heat treatment on microstructure and mechanical properties of TC17(α+β)/TC17(β) linear friction welded joints were studied. The results show that dynamic recovery and dynamic recrystallization had occurred in the weld. The microstructure of thermomechanically affected zone was stretched at varying degrees. After heat treatment the metastable phase of the weld precipitated dispersive phase and phase, and the primary phase of TC17(α+β) heat affected zone microstructure growed. The microhardness of welded joints is lower than that of base metal. The tensile strength and yield strength of the as welded joints reached 91.9% and 96.2% of that of base metal respectively. And the fracture position of the tensile specimen were at weld zone .After heat treatment，the hardness of base metal did not change significantly, and the microhardness of the joint was significantly increased. The tensile strength and the yield strength of the joints were equivalent to that of the base metal, and increased 11.9% and 8.2% when compared to that of the as welded joints.And the fracture position of the tensile specimen were in the base metal.