Abstract: Oxidation tests at 600-850 ℃ for 0.3-80 h were conducted on TC4 titanium alloy, and then the effects of oxidation on the macro morphology, cross section micro-hardness and cross section morphology of the alloy were studied. The oxidation behavior at high temperature was analyzed. The results show that with the increase of temperature and oxidation time, the surface oxide film of TC4 titanium alloy experienced the process of completion, cracking, spalling, severe spalling, peeling off completely. The thickness of oxygen diffusion layer formed on the near surface increased with the increase of temperature and oxidation time. The oxidation kinetics curve complied with parabolic law when the oxidation temperature was 600-650 ℃, linear law when the oxidation temperature was 750-850 ℃, parabolic law in the first 8 h oxidation and linear law with the oxidation time of more than 8 h when the oxidation temperature was 700 ℃. The hardness decreased with the distance from surface increasing at different oxidation temperatures for different times.