In this study, effects of solution-treatment and aging temperature on microstructure and mechanical properties of TC6 titanium alloy were investigated. The results show that when specimens were solution-treated at 800~840 _^oC, primary α and metastable β phases formed and they grew up with increasing temperature, which resulted in the slight increases in strength and ductility. The metastable β phase was also retained after solution-treatment at 880 _^oC though its stability was weakened, while at this moment double yield phenomenon was observed, which was attributed to stress-induced α″ orthorhombic martensite in the metastable β phase. When specimens were solution-treated at 920~960 _^oC, the strength increased and the ductility decreased in that primary α phase dissolved and a large amount of fine acicular α″ orthorhombic martensite precipitated from the metastable β phase. The alloy was almost composed of coarse α￠ hexagonal martensite after solution treatment above the β transus, which led to the decrease in strength and the brittle fracture during tensile test. In terms of different aging temperatures for solution-treated specimens (880 _^oC/1.5 h/WQ), the main microstructural changes were the precipitation of secondary α phase from the metastable β phase and its growth. Compared with solution-treated specimens, the specimens aged at 300 _^oC exhibited higher strength and lower ductility, and it can be seen that some secondary α phase and ω phase had precipitated from the β matrix. As the aging temperature increased to 400 _^oC, the maximum strength as well as minimum ductility was obtained. The specimens aged at 500 _^oC maintained the maximum strength, while the ductility was improved due to the sufficient diffusion of alloying elements. When the specimens were aged at 550 _^oC, these possessed the optimum balance of strength and ductility. The primary α phase gradually gathered to grow up and the lamellar secondary α phase apparently dispersed in the β matrix after aging at 600~700 _^oC, which led to the decrease in strength and the increase in ductility.