The protective layer prevents concrete corrosion and improves its durability.Different types of additional anti-corrosion coatings have different effects on improving the chloride ion corrosion resistance of concrete.Three surface film-forming coatings,three penetrating coatings,and one composite coating were selected,and the influence of coating types and water cement ratio on the chloride ion corrosion resistance of coated concrete was studied using the resistivity method.The results indicate that the coating can effectively inhibit the diffusion of chloride ions into the interior of concrete,and has a significant effect on improving the resistance of concrete to chloride ions.Under the same water cement ratio,the anti chloride ion corrosion effect of film-forming coatings is generally better than that of penetrating coatings,and composite coatings have the best performance.The water to adhesive ratio has a slight impact on the test results of the barrier effectiveness of the coating.