Nano-Al₂O₃ modified with 3-(glycidoxy propyl)trimethoxy silane(GPTMS) was dispersed in polyaniline / waterborne epoxy resin (PANI/EP) to get a homogeneous mixture. The new corrosion resistance coatings were achieved by mixing nano-Al₂O₃ based composites with PANI/EP and the hardener. The corrosion resistance and mechanical properties of the coatings were evaluated by electrochemical impedance spectroscopy, potentiondynamic polarization curve and so on. It is observed that nano-Al₂O₃ based polyaniline/epoxy coating has better mechanical and anticorrosion properties than the rest of the coatings. After immersion in 3.5% NaCl solution for 15 d, the impedance of the coating is 2.87×10⁷ Ω·cm², three orders of magnitude higher than that of the pure epoxy coating. The adhesion of the coating is 0 grade and the hardness is 6H, which is higher than that of other coatings. Additionally, the SEM images show that the nano-Al₂O₃ particles are uniformly dispersed in the polyaniline/epoxy coating, and the particles adhere tightly with the organic matter without obvious agglomeration. It is found that a dense passivation layer appears between the coating and the metal interface.