Abstract: Ti-6Al-4V-4Mo alloy was treated by solution at different temperatures and aging at 550 ℃for 6 h.The effects of solution treatment at different temperatures on the microstructure and mechanical properties of Ti-6Al-4V-4Mo alloy were studied.The results show that in the range of 800-860 ℃, with the increase of solution temperature, the precipitated dispersed phase in Ti-6Al-4V-4Mo alloy increases gradually after aging treatment, and the grain size does not grow obviously.When the solution temperature reaches 890 ℃, the dispersed phases in the aged alloygather and the grains tend to grow.In the range of 800-920 ℃, with the increase of solution temperature, the tensile strength and yield strength of Ti-6Al-4V-4Mo alloy after aging treatment increase gradually, while the elongation decreases gradually.The tensile strength, yield strength and elongation of Ti-6Al-4V-4Mo alloy solutin treated at 860 ℃and 550 ℃×6 h aging treatment are 1124 MPa, 996 MPa and 14.6%respectively.