The effect of increase diameter of coal particles on pulverized coal combustion to produce pollutants such as NOx, CO, CO2 and C in a 2D combustion chamber have been studied in this research by finite volume method. The numerical method is a generalized finite rate formulation, known as the Magnussen model, which is based on the solution of species transport equation for reactants and product concentration. The diameter of the pulverized coal varied from 0.0001 m to 0.0004 m which enters by the rate of 0.1 kg/s from the center of furnace. Moreover, air was preheated by a high-temperature gas generator, and the preheated oxidizer temperature could achieve  1400 C. The results show that by increasing the diameter of pulverized coal, the rate of formation of pollutants as well as NOx and the temperature of the flame decreased.