The invention relates to a closed circulating system suitable for an aerospace engine. Supercritical state fluid serves as a working medium, and the characteristics that the supercritical state fluid is large in heat capacity, extremely high in heat exchange efficiency, quick in response and low in viscosity are fully utilized so that the whole circulating system can be high in energy transmission capacity and small in flow resistance and can well adapt to changes of working conditions. The system can fully use heat released by cooling of high-temperature inflow air, and comprehensive management of engine energy can be achieved. The closed circulating system is used for the aerospace engine and can overcome defects of an existing engine precooling scheme so that the engine can meet the requirements of a hypersonic aircraft and a single-stage-to-orbit aircraft which can be repeatedly used.