Two inorganic metal nano oxides (nano tin oxide,SnO2,nano tin antimony oxide,ATO) were selected as the fillers for epoxy resin coating,a composite coating was prepared on the surface of Q235 carbon steel by spin coating method.The electrochemical impedance method was used to study the corrosion resistance of Q235 carbon steel in 3.5%NaCl solution.The electrochemical test results show that the protective efficiency of the epoxy composite coating with 3% mass fraction of nano ATO reaches 79.36%,higher than the protective efficiency of 60.38% of the epoxy composite coating with SnO2.This may be because the ellipsoidal structure of nano ATO plays an effective filling role in the composite coating,thereby improving the coating density.The salt spray test results show that the addition of trace nanoparticles can significantly enhance the salt spray resistance of the composite coating and improve the service life of the coating.