Supersonic combustion ramjet engine work flow field are thin. Therefore, We have to use micro particle to analyze. The macro continuum hypothesis is no longer suitable. This article use one of the Numerical Solution to simulate DSMC. It is precise and used a lot of analyze recently. This article adopted the variety of Scramjet inner flow field by DSMC. We consider the situation of fuel ignition and air mixing. How to achieve good mixing efficiency has become concerned about the direction of the research, therefore, for a variety of different the combustion chamber configuration calculation and analysis its mixing efficiency.