By the NSS test and the test in SO 2 gas atmosphere and detecting the  corr - t curves, R p- t curves and the cyclic voltammogram curves, the corrosion resistance of the electroplated Zn Co alloy coating was studied. The corrosion resistance of the electroplated Zn Co alloy coating is three times higher than that of the galvanized coating. Because the corrosion resistance of the Zn Co alloy coating is especially remarkable in SO 2 gas atmosphere, it is particularly fit to be used as a protective coating in industrial atmosphere. The reason why the Zn Co alloy coating has such a high corrosion resistance is that its corrosive product has a comparatively great role in depressing the corrosive process. By the NSS test and the test in SO 2 gas atmosphere and detecting the  corr-t curves, R p-t curves and the cyclic voltammogram curves, the corrosion resistance of the electroplated Zn Co alloy coating was studied. The corrosion resistance of the electroplated Zn Co alloy coating is three times higher than that of the galvanized coating. Because of the corrosion resistance of the Zn Co alloy coating is particularly remarkable in SO 2 gas atmosphere, it is particularly fit to be used as a protective coating in industrial atmosphere. The reason why the Zn Co alloy coating has such a high corrosion resistance is that that its corrosive product has a comparatively great role in depressing the corrosive process.