The effect of concrete surface hydropobation treatment against chloride penetration is studied by rapid test and in-site exposure test. It is shown that the silane impregnated layer can prevent the penetration of chlorides into the concrete substrate effectively and reduce the apparent chloride ion diffusion coefficient and surface chloride concentration; The apparent diffusion coefficient of surface treatment concrete can reduce by more than 50%, and improve the service life of concrete structure. Moreover, the depth of concrete convection zone can reduce due to silane impregnated layer for concrete in the marine environment of wetting and drying area.