The hydrogen powered hypersonic precooled combined cycle engine is an ideal candidate for next generation high speed clean civil aviation propulsion. It utilizes the energy inside the high speed air flow to power the air compression, in order to improve engine performance. Paralleled heat release and compression system, with several separated channels, is proved to be a crucial component to guarantee the favourable performance of the hypersonic precooled combined cycle engine. The system can sharply reduce the fuel consumption and cycle compressor pressure ratio (over 34% reduction in fuel consumption and over 45% reduction in cycle compressor pressure ratio, compared with ordinary single-route flow path design). The system is theoretically and quantitatively analysed. Operation mechanism, parameters design, feasibility and installing effects of the system are discussed. A performance simulation model is built for the paralleled system. The equivalent component method is proposed for measuring its effect on the engine overall performance. Inside the system, higher compression efficiency, lower pressure loss, more branches, higher heat transfer capacity and heat exchanger effectiveness can enhance the performance, while the feasible region, weight and size effects, and technical risks cannot be ignored either. For the engine, the installation of the paralleled system remarkably improves the engine performance and simplifies the compressor design. The paralleled system, with its advantage of coolant flow and compression work reduction, also can be beneficial to other applications in energy and power field.