The durability of reinforced concrete caused by chloride salt under high temperature，high humidity and high salt environment in South China is a major problem. A hydrophobic surface structure of concrete provided by silanes impregnated helps to reduce the depth of chloride penetration. Previous studies are all based on laboratory and exposure tests. However，there is little reported information about the long-term corrosion protection of silane impregnated concrete in South China marine environment. Herein，the water absorption，chloride content and corrosion potential test are applied to assess the corrosion protection of silane impregnated concrete after 12 years’ service. The results indicate that the silane treated concrete surface is compact and intact，while the hydrophobic performance is degreased with the increased service life. The limited diffusion rate of chloride in concrete and strong passivation of steel rebar resulted from silane contribute to a significantly improved durability of concrete structure.