The pressure regulator’s structure and working process in aviation oxygen supply system (OSS) were explored and discussed. Based on reverse-type pressure regulator, combining with the theoretic structural model and dynamics of gas flow, the mathematic models for steady and dynamic characteristics were built. By the numerical simulation on MATLAB/Simulink and the theoretic analysis to regulator performance, the steady and dynamic characteristics of regulator were analyzed. The simulation results are in good agreement with those measured in the experiment.They show that the analytical models are correct and the simulation method is in accordance with the precision requirements. By using the mathematic models and the simulation method,the affection to the steady characteristic by regulator structural parameters is analyzed and the major parameter is found to affect the dynamic characteristics. The study and its conclusions are useful for the design of congener regulators and the system analyses.