Through long-term exposure test and engineering investigation,the long-term protective effect of surface coating on marine concrete structure is studied,and the influence of coating on service life of concrete structure is quantitatively evaluated.The research shows that the coating can effectively isolate chloride ion intrusion,significantly improve the service life of concrete structures,and the coating system using epoxy asphalt and chlorinated rubber surface layer has better anti-aging performance.However,due to the influence of the actual service structure by working load and complex painting construction environment,the chloride ion concentration in the engineering structure is significantly higher than that exposure test.In the actual service environment,the surface chloride ion concentration increases gradually with the extension of service time,and the surface chloride ion concentration conforms to the linear function model with service time(Cs=kt）.Considering the effect of coating on the time-varying characteristics of chloride ion concentration on concrete surface,a quantitative evaluation method for durability life of coated concrete structures is established.