Corrosion of reinforcement is a common phenomenon in reinforced concrete structures, the process of concrete hydration makes the concrete increase in strength but at the same time reduces the pH in the concrete, which makes the reinforcement loss of passive rust resistance. With the penetration of harmful agents such as chloride ions and carbon dioxide, after a while they will directly affect the reinforcement and cause corrosion. This paper focuses on presenting the mechanism of steel rust formation in concrete, and the issues that need to be taken to limit the occurrence of steel corrosion are also discussed. In addition, the paper gives some causes leading to the penetration of carbonate and chloride into concrete, from which the construction engineer can prevent steel corrosion in concrete.