Space nuclear reactor power, with the advantages of high energy density, high output power, long duration, and minimal influence from the external environment, is the preferred route for energy supply for future high-power long-life space missions and deep space exploration missions. Based on the developmental requirements and characteristics of different design options for megawatt-class space nuclear reactors, a technical scheme for a megawatt-class small lithium-cooled space reactor is designed. This scheme uses a lithium-cooled reactor coupled with a Brayton power conversion system that is lightweight and durable. The key technologies involved in the design are reviewed. Developmental progress of technical analysis and demonstration, verification prototype systems, and experimental platforms is presented. Suggestions and comments for developing high-power space nuclear power in China in the future are presented.space nuclear reactor, lithium-cooled reactor, Brayton power conversion system