As the concept of aerospace design is changed, research objectives of titanium alloys also changed from high strength to high damage tolerance. High strength, high toughness titanium alloys with damage-tolerance have been investigated under the support of a national project since 2003. TC21 titanium alloy is the first Chinese-developed high strength, high toughness and damage-tolerance titanium alloy. The mechanical property of TC21 alloy is sensitive to solution temperature and aging temperature. The rods of TC21 alloy with the diameter of 20mm and 90mm possess good mechanical properties after solution at 900°C followed by aging at 600°C.