Abstract: As the time goes by concrete dams have become ageing gradually, which is characterized by foundation variation, mass changed, erosion being become more serious, erosion intensified, cracks developed, the disaster from freezing and melting growing on and the equipment of flood discharge corrosion being worse. The geometry of concrete dam, its mechanical index and function as water retaining and discharging will gradually transform to the unfavorable condition for safety operation. So inspection and monitoring work should be strengthened on the concrete dam ageing, meanwhile, the measures should be taken to prevent from ageing in order to make it being long used.