Abstract: Due to the low boiling point for cryogenic propellant, the cryogenic rocket engine and delivery pipelines must be fully cooled before startup. Pre-cooling methods largely influence the complexity of the pre-launch rocket test procedure and the adaptability of delayed launch. Therefore, it is needed to comprehensively consider amounts of factors. In this paper, by comparing three pre-cooling methods in detail, selection principles are given. Finally, a model of the forced circulation pre-cooling system for hydrogen is developed with AMESim. According to the system characteristics, it is found that the tank pressure, the speed of the circulating pump and the pressure in the isolated cavity influence the cooling effect. The simulation results show that the pressure difference between the outlet pressure of the circulating pump and the pressure in the isolated cavity is the key factor, and the bigger, the better.