TA18 alloy was used as the base material to investigate the effect of thermal oxidation (TO) on titanium alloys. The samples were subjected to TO treatment in a conventional muffle furnace at the same duration (210min) for different temperatures under air atmosphere. The results showed that an oxide layer comprised of rutile TiO2 and a small amount of Al2O3 were formed for samples thermally oxidized at 700°C and above, and both rutile and Al2O3 peaks increase with the treating temperature. The surface hardness increased significantly with the treating temperature due to the formation of a thin oxide layer and an oxygen diffusion zone in TO process. The wear test results showed that TO process can significantly improve the wear resistance, and the wear resistance is a function of the treating temperature, with 700°C being the optimum temperature to improve wear resistance of TA18 alloy for the duration of 210min.