Cryogenic Rocket Stage uses on-board pressurisation modules for maintaining tank pressure during flight. Efficient cryogenic stage pressurisation is crucial for achieving the desired performance and payload capacity of a rocket. Properly pressurised tanks ensure stable propellant flow rates, consistent combustion in the engines, and overall mission success. Various methods, including regulator and on/off pressurization modes, are employed. Cryogenic stages utilize an onboard Tank. This selected system utilizes a high-pressure gas stored in bottles submerged within cryogenic propellant tanks. A High-Pressure Regulator regulates the gas to a lower pressure, which is then heated via a Heat Exchanger before being introduced into the propellant tank through an orifice. This continuous pressurisation ensures precise control of tank pressure, with 25–30% pressurant delivered through a bubbler orifice to uphold sub-cooled propellant bulk mass temperature. A mathematical model of the Tank Pressurisation Module is developed using AMESIM. The model developed in LMS AMEsim 14.0, integrates pneumatic components design, control, and signal interfaces, resulting in a software-specific executable file. Extensive simulation trials led to design optimization, subsequently validated through laboratory level tests. The utility of this dynamic model proved significant in comprehending the pressurisation module's functionality and assessing its performance in a flight setting.