For the purpose to explore the durability of concrete structures in tropical marine environment, main destruction,carbonation depth, free chloride concentration (Cf) and total chloride concentration (Ct) of coral concrete were studied through site investigation and laboratory experiments on the South China Sea.The results showed that:In the South China Sea islands engineering, more wind, high temperature corrosion of marine environment has strong destructive effect on coral concrete structure, the main failure characteristics are cover crack, collapse,steel bar exposed, steel corrosion of concrete;the carbonation depth rule of all coral concrete is atmosphere zone >splash zone>tidal zone;Due to the nature of coral aggregate porous, so the water or sea salt chloride is easier to access to the concrete structure, coral concrete chloride concentration was much larger than ordinary concrete chloride ion content at the same depth.So in the South China Sea islands engineering, we must improve the anti-chloride permeability of coral concretes, especially improve its density, which will enhance the service life of these structures.