Abstract: In this paper, recentprogress in the research of air-breathing hypersonic propulsiontechnology is briefly reviewed, key problems arising from Scramjetresearch are discussed, and possible methods are presented forenhancing scramjet performances, including hypersonic flowcompression with a low total pressure loss, three-dimensionalvortex generation for supersonic mixing, preheated carbon-fuelinjection, combustor optimization for combustion control,reduction of engine wet-area for lowering friction drag, andcatalyzation of dissociated high temperature gases for moreheat-release. In consideration of the thermo-efficiency of theconstant pressure cycle, the detonation process with higherthermo-efficiency is suggested to apply to the hypersonicpropulsion, relevant methods on the detonation propulsion areintroduced and related problems are discussed. It is necessary tocarry out careful reasoning on the development of hypersonicpropulsion, and to explore new concepts and technologies to drivefurther hypersonic vehicle researches.