Abstract: The working process of the H₂/O₂ engine full-flow staged combustion cycle is discussed,and the system sketch of the rocket engine based on this cycle is presented.Based on the development status of the H₂/O₂ rocket engine, the system parameter balance calculations were executed.The calculated results show that the full-flow staged combustion cycle yields a lower temperature of the pilot burner and the turbine working gas compared to the fuel-rich staged combustion cycle engine with the same power output.The advantages of the full-flow staged cycle are discussed.It is believed that reliability and performance of the engine with this kind of cycle are superior and the full-flow cycle engine can satisfy the high reliability,low cost and reusable requirement.