Increasing cryogenic propellant subcooling remarkably benefits the long-term on-orbit storage of cryogenic fuels. Literature research and theoretical analysis were conducted to study the working processes and research status for four subcooling schemes

and their advantages and disadvantages were also analyzed. On this basis

a research approach in this field was proposed for guiding the domestic researches. Several valuable conclusions were drawn as follows: (1) Based on the cost consideration

an operating procedure for subcooling operation after fuel filling process is suggested and the subcooling equipment should be located close to the target tank.(2) A liquid nitrogen pool boiling can be used to cool the cryogenic liquid oxygen and liquid methane.(3) Helium injection approach is only suggested to cool the small-scale liquid hydrogen since it costs massive helium gas.(4) Due to excellent characteristics including less total weight and energy input

thermodynamic cryogen subcooler (TCS) approach has a better application prospect in liquid hydrogen subcooling obtainment. This research provides a reference for the domestic researches of cryogenic propellant subcooling.