Endothermic hydrocarbon fuel is regarded as an optimal fuel for a scramjet with regenerative cooling,which provides extra cooling through endothermic chemical conversion to avoid the severly limited cooling capacity when conventional fuels are adopted for cooling.Although endothermic cooling is proposed from the view point that the heat sink of a conventional fuel is insufficient,the heat-absorbing through endothermic chemical reaction is actually a chemical recuperation process because the wasted heat dissipated from the engine thermal structure is recovered through the endothermic chemical reaction.Therefore,the working process of a scramjet with endothermic hydrocarbon fuel cooling is a chemical recuperative cycle.To analyze the chemical recuperative cycle of a chemically recuperated scramjet engine,we defined physical and chemical recuperation effectivenesses and heating value increment rate,and derived engine performance parameters with chemical recuperation.The heat value benefits from both physical and chemical recuperations,and it increases with the increase in recuperation effectiveness.The scramjet performance parameters also increase with the increase in chemical recuperation effectiveness.The increase in chemical recuperation effectiveness improves both the performances of the fuel cooling system and the combustion system.The results of analysis prove that the existence of a chemical recuperation process greatly improves the performance of the whole scramjet. Endothermic hydrocarbon fuel is considered as an optimal fuel for a scramjet with regenerative cooling, which provides extra cooling through endothermic chemical conversion to avoid the severly limited cooling capacity when conventional fuels are adopted for cooling. Although endothermic cooling is proposed from the view point that the the heat sink of a conventional recuperation process is the heat-absorbing through the endothermic chemical reaction is the heat-absorbing through the endothermic chemical reaction.Therefore, the working process of a scramjet with endothermic hydrocarbon fuel cooling is a chemical recuperative cycle. analyze the chemical recuperative cycle of a chemically recuperated scramjet engine, we defined physical and chemical recuperation effectivenesses and heating value increment rate, and derived engine performance parameters with chemical recuperation. heat value benefit s from both physical and chemical recuperation, and it increases with the increase in recuperation effectiveness. the scramjet performance parameters also increase with the increase in chemical recuperation effectiveness. increase in chemical recuperation effectiveness improves both the performances of the fuel cooling system and the combustion system.The results of analysis prove that the existence of a chemical recuperation process substantially improves the performance of the whole scramjet.