This paper has developed a computational platform of a supersonic inlet with variable geometry, using MATLAB/SIMULINK A method based on this for simulation of a complicated model has been presented. The correctness and reliability of the new method have been testified by simulating the stationary flow fields of an inlet under back pressure gust and gust of parameters of incoming air flow. Based on the method, the dynamic behavior of the terminal normal shock wave in the inlet has been obtained by carrying out a simulation of the object model of an inlet, and it's dynamic and stationary characteristics have also been obtained. A complicated distributed-parameter problem of a 1D supersonic inlet has been transformed to a 0D problem which reduced the inlet model and solved the concentrative-parameter difficult that could never be realized in system analysis and controller design. The work of the study has much significance for future work.