Abstract: The metastable β-TB5 titanium alloy was prepared by the twice vacuum self-consuming arc melting.The effect of Al content on microstructure and mechanical properties of the alloy treated by solution (800 ℃×10 min)and solution-aging (800 ℃×10 min+540 ℃×8 h)was studied.The results show that the microstructure of the alloy was almost same with the one after solution as the Al content was 2.8wt%-3.2wt%.No inarked difference was found anong the microstructure of the alloys with different compasition afcer solution and aging.As the inerease of Al content,the strength of all the alloys in different states first increased and then decreased,and the tonghness tuned bad.The alloy had the highest strength the tensile,strength of 1 300.0 MPa in solution and agingstate,and the elongation was 8.8% as the Al content was 3.0wt%.