Al₂O₃ thin films are deposited on the surface of 304 stainless steel by electrodeposition-pyrolysis, and the effects of electrolyte concentration and electro-deposition voltage on the oxidation behavior of Al₂O₃ thin film at 900 ℃ are investigated. Macroscopic surface morphologies, XRD analysis and oxidation kinetics curves show that the electrodeposition-Al₂O₃ thin films reduce the partial pressure of oxygen at the initial oxidation stage on the substrate surface, promoting the selective oxidation, thus the oxidation resistance of 304 stainless steel is significantly improved. The high temperature oxidation resistance of Al₂O₃ film prepared under voltage of 25 V and aluminum nitrate alcohol solution of 0.10 mol/L is the best.