Abstract: Using the finite element state-variable model for one-dimensional ideal gas flow,a modularized simulation model was established,and then the working process was calculated for the tank pressurization system of LRE test-bed.Detailed distribution curves of state parameters for the pipe net were obtained,which could be used to analyze the working process of the system and the function of every component.The mathematical model and the method of modularized modeling and simulation were validated to be effective and versatile.