Epoxy polymers have been widely used in a protective coating and adhesive due to its strong adhesion, high chemical resistance, and good processing characterisitics. However; epoxy coatings absorbs moisture easily, and the diffusion of absorbed water into the epoxy.steel interface weakens the interfacial adhesion strength between epoxy and steel in corrosive enviroment, due to the presence of hydrophilic hydroxy group in the cured network (epoxy/amine reaction). In this study, commercial epoxy polymer was chemically modified by .-glycidoxypropyltrimethoxysilane monomer under the catalysis organotin compound via the reaction between hydroxyl group in epoxy polymer and alkoxy group in silanes, aiming to enhance the corrosion performans of epoxy polymer. Commercial epoxy polymer and silane modifed epoxy polymer were characterized by NMR spectroscopy, FTIR spectroscopy, epoxy equivalent weight measurement, contact angle measurement, surface energy measurement, hardness test and MEK double-rub test. The results showed that .-glycidoxypropyltrimethoxysilane has been successfully grafted to epoxy polymer. Corrosion performance was evaluated by salt spray test acording to ASTM B117. The results showed that the chemically modified epoxy coating perform an improvement in resistance againts the penetration of water in polymeric resin and beter protectiveness on metalic corrosion.