The oxidation behavior in air of Al₂O₃/Ti₂AlN composite at temperature of 900 ℃ 1 000 ℃ and 1 100 ℃ in 20 hours were studied by oxidation weight experiment, back scanning electron imaging(BSE) and energy dispersive spectrometer (EDS). The results show the oxidation behavior of composite obeys a parabolic law from 900 ℃ to 1 100 ℃. The oxidation weight gain respectively is 2.78×10_-2 kg/m₂、10.4 ×10_-2 kg/m₂、21.9 ×10_-2 kg/m₂. The parabolic rate constant corresponding to 1.08×10_-8 kg₂/m₄s、1.44×10_-7 kg₂/m₄s、6.56×10_-7 kg₂/m₄s. the oxide activated energy is 274 kJ/mol. The composed of oxide layer are TiO₂ and Al₂O₃. The good oxidation resistance of Al₂O₃/Ti₂AlN composite is coming from the continuous outer Al₂O₃ layer. The structure changes of oxide layer is due to The temperature effect the diffusion rate of Ti₄₊, Al₃₊ ions outward and O_2- inward, it also effect the nucleation and growth rate of TiO₂ and Al₂O₃. Those are the reason of the changes of oxide layer structure at different temperature. To control the interface between the matrix and oxidizing atmosphere is the key to improve the Al₂O₃/Ti₂AlN composite oxidation resistance