The nitrogen oxide emission is known as a potentially hazardous pollutant in reacting flows. To improve this process, it is of fundamental importance to take into consideration environment protection through reduction of fuel consumption in addition to increasing combustion efficiency. The control of NO emission from the combustion process is an important design criterion in modern gas turbine technology. In the present work a two-dimensional combustion simulation is developed for a model gas turbine combustion chamber. The k−ε turbulence model and the eddy dissipation concept model are applied for flow predictions and reaction rate simulation respectively. The flow field pressure linked equations are solved using the SIMPLE algorithm. In the present work, the thermal and prompt NO formations are estimated and calculated for three different methane, propane and pentane fuels. Also the effects of equivalence ratio and primary aeration on nitrogen oxide emission are considered. Results of numerical simulation show that the nitrogen oxide emission significantly affected by the equivalence ratio for all three type of fuels. Also by applying primary aeration the averaged nitrogen oxide production can be significantly reduced.