Objective To study the protective performance of Al₂O₃ nanoparticles epoxy composite coating of steel. Methods The Al₂O₃ nanoparticles were prepared, and then added into the epoxy coating, coated on the steel as a film. The Al₂O₃ nanoparticles were characterized by XRD and SEM. The anti-corrosive properties of the composite coatings in the solution of 3. 5% NaCl were evaluated by electrochemical noise and electrochemical impedance spectroscopy. Results The average size of Al₂O₃ nanoparticles was 75 nm. Based on the time and frequency domains analysis of electrochemical noise data, the analysis of electrochemical impedance spectroscopy and data fitting, it was found that the composite coating with 0. 1% Al₂O₃ nanoparticles ( as a percentage in the weight of epoxy resin) had the best protective performance on steel. Conclusion The epoxy coating supplemented with a suitable amount of Al₂O₃nanoparticles showed significantly improved protective performance on steel.