The frequent exposure of the estuarine ship lock to the special corrosive environment of alternating dry and wet conditions and saltwater intrusion can accelerate the deterioration of the anti-corrosion coating on the metal structure,seriously threatening its service life and operational safety.To address this issue,a high-frequency dry-wet cycle automated testing machine is designed to simulate the actual service environment of the estuary ship lock.Five typical heavy-duty anti-corrosion coating systems are selected for indoor accelerated corrosion tests.The key parameters of the coating systems,such as gloss loss,adhesion,low-frequency impedance modulus,and open-circuit potential,are analyzed for coating anti-corrosion effectiveness using methods such as gloss loss analysis, adhesion testing,and electrochemical impedance spectroscopy analysis.The influence of coating materials and coating thickness on the anti-corrosion performance is emphasized,and the deterioration laws of traditional heavy-duty anti-corrosion systems in the alternating dry and wet conditions and saltwater intrusion coupling environment are revealed.The results show that the adhesion and gloss retention of polyurethane topcoat are superior to those of chlorinated rubber,and the electrochemical indicators can be significantly improved with the increase of coating thickness (such as the 720 μm system).The coating deterioration shows a characteristic of rapid initial deterioration followed by a gradual slowdown.The overall performance degradation is closely related to the film thickness and material properties.Comprehensive analysis indicates that the epoxy zinc-rich primer,epoxy mica intermediate coat,and polyurethane topcoat (720 μm system) perform better overall.