Reinforced concrete may be corroded in chloride ion environment which will be a danger to structures safety. Silane hydrophobic agent is a kind of agent to protect the reinforced concrete. This technology has been applied to many projects. But during the application of the agent， differences are reflected. There is a divergence of views, and the divergence is summarized and discussed in this study. The protective mechanism and the application status at home and abroad of the silane hydrophobic agent are introduced. According to previous researches and engineering applications, the differences on concrete durability using the silane hydrophobic agent such as the anti-aging, hydrophobicity, resistance to chloride ion penetration, anti-carbonation and freeze-thaw resistance are analyzed. During construction, influence factors including concrete surface moisture, grinding of carbonized layer and slurry, environmental temperature and wind velocity are discussed too. Finally, the continuous researches on application of the silane hydrophobic agent to reinforced concrete must be carried out, especially on its durability and suitable scale by action of various environmental factors.