Abstract: With the fast development of space exploration, it is of great importance to conduct research and design of the space nuclear reactor power featured with high power, safety and reliability. This paper focused on the key issues of thermal-hydraulic characteristics of space nuclear reactor power at home and abroad, including the study on steady-state and transient-state analysis of space nuclear reactor power system, 3D flow and heat transfer in the reactor core, analysis of the static and dynamic thermoelectric conversion system, key phenomena of thermal-hydraulic experiments. Based on the literature review, the current development and research trend of space nuclear reactor power was summarized. This paper would provide some valuable suggestions for design and thermal-hydraulic characteristics study of the space nuclear reactor power.