The spacecraft propulsion system puts forward an urgent need for cryogenic propellants with high density, low pressure storage and on-orbit reusable tanks. The research on the self-pressurization mechanism of cryogenic tanks and the pressure control technology have become the main factors affecting the on-orbit application of cryogenic propellants. In this paper, a numerical model of heat transfer and pressure control of cryogenic liquid tanks under microgravity conditions is established. By comparing and analyzing the self-pressurization model of cryogenic tanks, the best finite element model is obtained, and the self-pressurization mechanism of cryogenic tanks is analyzed, which lays a foundation for low temperature pressure control. The research content of the follow-up work on the pressure control of cryogenic propellant on-orbit storage is proposed, which provides reliable theoretical support for the storage and transportation of cryogenic propellant in space in the future.