In this chapter, the important place of hydropower generation–the powerhouse of hydropower station is introduced. First of all, the four basic types of powerhouse, and the composition of buildings and equipment, are introduced in detail. Secondly, the main hydraulic machinery and electrical equipment in the powerhouse is summarized, and the layout of the main structural layer of the main powerhouse is presented, including the generator layer, hydraulic turbine layer, and spiral case layer. On this basis, the spatial structure design of the main powerhouse, including the calculation method of the main elevation and the determination of the plane size, is discussed. In addition, the auxiliary equipment of the powerhouse is introduced, including hydraulic machinery auxiliary equipment, electrical auxiliary equipment and operation and maintenance equipment, and the compositions of each equipment are explained. Then the function and classification of the auxiliary powerhouse are introduced, as well as the corresponding layout principle of the powerhouse. Finally, the influence factors of the layout of the whole powerhouse project and the layout principles of the main buildings are summarized.