Computational fluid dynamic (CFD) could analysis the flow characteristics in the nozzle exit with fluid condition variation. Consequently, the purpose of this paper is to show that the fluid temperature and velocity field formed in the nozzle exit dominates the understanding for flow phenomenon. High fluid velocity can cause such a high temperature in the test gas that dust the particles grow. For this reason the flow conditions with air-air, air-vapor as test gases were used in this paper. The most important result to come from the CFD was the existence of the shock wave structure which was a dominant influence on the flow characteristics in the nozzle exit. Specially, It has an advantage to confirm the normal shock wave location because the temperature field variation of the flow distinguish clearly through mach disc.Also, the temperature through normal shockwave is at around 2.0 times higher than in atmosphere fluid condition. Consequently, this can be used as a good technical background for the design of rocket engine.