Abstract: The low-carbon transition of energy and power system is the key to achieving carbon peak and carbon neutrality, which is related to China's sustainable economic and social development. With the boundary of economic and social development goals, this paper analyzes the time sequence of fossil energy withdrawal and non-fossil energy replacement in China, on the premise of keeping the bottom line of energy security strategy. Moreover, we compares and analyzes the power transition scenarios under different energy supply situations, and proposes the pathway of building zero-carbon power system. Suggestions are put forward to promote China's low-carbon energy and power system transition from the following aspects: firming development goals, laying a solid foundation for energy security, controlling the pace of transition, strengthening the guidance of technology, and innovating institutions and mechanisms.