Abstract: Titanium and its alloy are important space metal materials, which play an extremely important role in the field of aerospace.The tensile properties of Ti-6Al-4V ELI(extra low interstitial) titanium alloy at high temperature(350 ℃), room temperature(20℃) and ultra-low temperature(-253 ℃) were studied and the mechanical property indexes of Ti-6Al-4V ELI titanium alloy at different temperatures were compared. The fracture morphology characteristics were analyzed. The results show that Ti-6Al-4V ELI titanium alloy presents high mechanical properties and brittle fracture characteristics at ultra-low temperature and its tensile strength can reach more than 1900 MPa. At room temperature and high temperature, the alloy exhibits good plasticity and toughness with ductile fracture characteristics. Due to the excellent mechanical properties in a wide temperature range, Ti-6Al-4V ELI titanium alloy is an essential metal material for the development of aerospace field in the future.