Air vehicles have began to develop with advancing technology. In order to increase the thrust and reduce pollutant levels at high speeds, researchers focus on different combustion techniques. For this purpose, within the scope of this study, A Scramjet engine combustor has been studied. The effect of reduced oxygen concentration in the air on Scramjet engine combustion was investigated. A hydrogen fueled Scramjet engine is used. In order to seek oxygen concentration effects on combustion characteristics of the Scramjet engine combustor, oxygen concentration in the oxidizer (by mass) was reduced, and the concentration conditions were performed at 23.2%, 21%, 20%, 19%, 18%, 17%, 16%, and 15%. Fort he modelings Reynolds Average Navier-Stokes (RANS) standard turbulence model is preferred for turbulent modeling. A combination of Eddy Dissipation and Finite Rate combustion model was selected to model combustion. The data obtained through the modelings were compared with the experimental data, and the results are in good agreement with the measurements. The results predicted are evaluated, and it was concluded that the velocity increased as the oxygen concentration was increased. It was also predicted that the temperature difference caused by the oxygen concentration decreased with moving away the flame position from the combustor.