The most critical component in an aerospace tank pressurisation system is a pneumatic pressure regulator with helium gas as the medium. The current paper focused on dynamic analysis of high pressure, spring-loaded, cryogenic medium pressure regulator. In order to evaluate its dynamic behaviour, a nonlinear model has been developed based on the fundamental equations by considering various forces–pressure forces, spring forces, bellow forces and Coulomb friction forces. The simulation is carried out for nominal operating conditions of the pressure regulator using commercial available AMESIM simulation tool. The effect of damping orifice size and downstream ullage volume are studied and obtained results are presented in the paper. Also experimental tests have been carried out for the same parameters to validate the simulation model using a proto model developed in-house with emphasis on machining of various precise parts of the high pressure regulator. These parts are manufactured in-house using high precision surface grinding, jig boring, electro discharge machining process, etc. The machined parts are realised to achieve precise sliding diametrical clearances between 32 microns and 50 microns, eccentricity within 20 microns and average surface roughness of 0.4 microns. The dimensional parameters of the machined parts are evaluated using the co-ordinate measuring machine (CMM), Talyrond and Talysurf equipments. The simulation results and experimental test results are found to be in good agreement. The developed model serves as a tool for optimisation of the regulator performance parameters. © 2020 Informa UK Limited, trading as Taylor & Francis Group.