Abstract: Using universal material testing machine and split Hopkinson pressure bar,quasi-static and dynamic mechanical properties of TC21 titanium alloy treated by four kinds of heat treatment technologies had been tested respectively and effects of heat treatment on the quasi-static,dynamic mechanical properties and strain rate sensitivity of TC21 titanium alloy had been studied.The results show that the binary microstructure has the best plasticity,but lower intensity;Tri-modal microstructure has better plasticity and strength;Basket-weave microstructure has higher strength,but poor ductility;Solution aging microstructure has higher strength and better plasticity than the basket-weave microstructure under the condition of quasi-static deformation.Under high strain rates,dynamic mechanical properties of four kind of microstructure of TC21 titanium alloy are similar to that of quasi-static mechanical properties.Four kinds of microstructure of TC21 titanium alloy are very sensitive to strain rate.The strain rate sensitivity subsequence of four kinds of microstructure of TC21 titanium alloy is solution aging microstructure,basket-weave microstructure,tri-modal microstructure and binary microstructure in turn according to in sort descending.