Abstract: Based on the landform and geological conditions of selected concept design site in the mountainous and hilly region, the suitable underground nuclear island form and overall arrangement basic model are selected. Considering the benchmark flood level, amount of earthwork excavation engineering and water head of circulating water, and so on, the ground plateau elevation for the first platform is determined, and based on the thickness of the coverage and the reactor cavity height, the ground plateau elevation of the second platform is determined. In accordance with the principle of overall arrangement, referring to the standards and regulations, the general arrangement of underground nuclear power plant CUP600 is studied to determine the main plant technical indicators of the layout scheme.