TA18 alloy was chosen as the experimental material. The samples were subjected to thermal oxidation treatment in a conventional muffle furnace under air atmosphere. The effect of thermal oxidation temperature on the microstructure and performance was studied. The microstructure, phase constituents, hardness, corrosion and wear resistance were evaluated by optical microscope (OM), XRD, micro-hardness tester, immersion test in 36%–38% (mass fraction) HCl solution, friction and wear tester. The results showed that the oxidized film was consisted of oxide layer and oxygen diffusion zone beneath, with rutile TiO₂ as the predominant phases along with a small amount of Al₂O₃, and the amount of rutile increased with the increase of oxidation temperature. The results also showed that the surface hardness increased with the increase of oxidation temperature of 500–800 ℃ , while decreased beyond 800 ℃. The corrosion and wear resistance was obviously improved after thermal oxidation, and 800 ℃ was the optimal temperature to improve the corrosion resistance in 36%–38% (mass fraction) HCl solution, and 700 ℃ was the optimal temperature to improve the wear resistance.