This paper analyzed the microstructure of Ti6Al4V titanium alloy after different heat treatments. The tensile experiment and instrumented impact test were done. It was studied that the microstructure, mechanical properties and impact toughness of Ti6Al4V titanium alloy were affected by the solution and aging treatment. The relationship among the microstructure, impact fracture characteristic and mechanical properties was analyzed by metallurgical mi-croscope and environment scanning electron microscope (ESEM). The results showed that the yield strength and ul-timate tensile strength were improved remarkably. The ductile increased firstly, then it decreased. The good compre-hensive properties can be gotten when the Ti6Al4V titanium alloy was treated in the condition of 960 ℃×1h WQ and 500 ℃×4h AC. The σ0.2 is 1050 MPa. The σb is 1120 MPa and Ak is 46.22 J. The microstructure of the tita-nium alloy after solution and aging treatment was consisted of the β matrix and the precipitation of the α-phase. The lamellar β-phase and the α-phase structure of the small needle plexiform can enhance comprehensive properties.