Objective To study the effect on corrosion resistance of composite ceramic coatings were formed on Al-Si cast alloy by microarc oxidation (MAO) in electrolyte with α-Al2O3 microparticles. Methods Using SEM and XRD analysis of α-Al2O3 particles on the micro structure and composition of coating. and Through the polarization curve, ac impedance spectroscopy and neutral salt spray test evaluation of the corrosion resistance of coating. Results show that the incorporation of α-Al2O3 microparticles changed the microstructure and phase composition of microarc oxidation (MAO) coating. MAO coating had double-layer structure and was porous, what’s more the main phase composition was γ-Al2O3.and after adding α-Al2O3,the composite coating had much less porous and appeared α-Al2O3.In addition,α-Al2O3 particle also improved corrosion resistance of MAO coating. In the 3.5wt.% NaCl solution, the corrosion current density of MAO coating was 1.476×10-5 A?cm-2, Moreover the resistance of porous layer (Rp) and the resistance of barrier layer (Rb) of MAO coating were 0.259KΩ?cm2 and 69.18 KΩ?cm2 respectively, Resistant to salt spray test time was 1200 h. However, the corrosion current density of composite coating only was 28% of the MAO coating, And showed better corrosion resistance, the resistance of porous layer (Rp) of composite coating was 274.5 KΩ?cm2 and more than that of MAO coating. In addition the resistance of barrier layer (Rb) of composite coating were higher than MAO coating an order of magnitude, and resistant to salt spray test time was 1440 h. Conclusion α-Al2O3 microparticles can effectively improve the corrosion resistance of MAO coating.