Abstract: China has carried out a lot of research work in the field of deep space exploration （more than dozens of AU）but the ultra deep space exploration mission has not yet been launched. Interstellar exploration can greatly enhance the space exploration, improve the self-sufficiency of data required by space science research, and reach the international leading level in the world. Far away from Jupiter, satellites will get less solar mediation intensity, how to generate electricity and how to prevent the satellites too cold should be considered. So we need to design a reasonable energy system by considering the limit conditions about flight space environment, task life and weight. Based on the investigation of relevant tasks in foreign countries and the existing technical basis in China, the space nuclear energy system is selected as the main power solution. Meanwhile, the conceptual propulsion design is also considered, and the task assumption and key technologies to be developed are put forward.