Abstract: Tensile tests were conducted on TC21 Titanium alloy with basket microstructure in 0. 001s^-1 ～50s^-1 strain rate. Test results indicate that the alloy exhibits significant strain rate strengthening，strain hardening and strain-rate sensitive thermal-softening under strain. Strain-rate sensitivity of yield stress turns at 6s^-1. Strain hardening decreases with increasing strain rate while unstable strain and fracture strain under high strain rates are larger than those under low strain rates. Mechanism governing deformation is dislocation thermal activity. All specimens fracture in a ductile manner and the fracture mechanism is voids nucleation and growth.