Abstract: Corrosion of different degree exists on the gates which were built in the period of 1960～1980, especially serious on the side guide plate. The main formof corrosion is that the guide plate would get thinner, corrosion pit would appear at some parts of the plate. Corrosion would lead to leakage at the gate and increase the attrition of water seal. Traditional way of corrosion treatment was chiseling off the concrete of second- stage gate slot and change a newside guide plate. This is of the disadvantage that narrow construction area, long construction period and big effect to whole project. The paper introduced a newrepair way with the application of a newpolymer material, it’ s of the advantage that simple and fast construction, high strength of the material, big binding power. It would protect side guide plate fromcorrosion and because it is smoother than steel, it would decrease the attrition of water seal, reduce the fiction factor to 50% and lowthe lifting power. This technology was applied to reservoir gate and of good effect, worthy reference.