Abstract: This paper proposes the concept of hydrogeological structure of deep-incised river valleys. It aims to effectively prevent and control the hydrogeological problems that may be encountered in the construction and operation of water conservancy and hydropower projects. The proposal of this concept is guided by the theory of rock engineering geomechanics and is based on the understanding of rock mass structure and hydrogeological structure. In China, most of the hydropower projects are built in deep-incised river valleys in western areas. With regard to the geological and environmental features in the areas, this paper summarizes four types of deep-incised river valleys including bank slope type, river-paralleling type, river-crossing type and regional type. It also summarizes their corresponding characteristics. In addition, this paper also preliminarily expounds the control mechanism of these types of valleys on the engineering hydrogeological problems during the construction of hydropower projects.