The average diameter of equal burning speed and equal burn out rate of pulverized coal and their calculation method in numerical simulation of pulverized coal combustion were presented.The one dimensional combustion model of pulverized coal jet was applied to conduct calculation for coal particles with single diameter which equaled to the equal burn out rate average diameter

the equal burning rate average diameter and geometric average diameter respectively under various conditions

using the burn out process of coal particles which in accordance with Rosin-Rammler distribution as the comparison baseline.By comparison of burn out curves under the same condition

the optimal calculation method for average coal diameter was obtained.When using the equal burn out rate average diameter as the particle's single diameter

the burn out rate was very close to the calculation result of coal particles with distributed diameters during the whole combustion.Applying the equal burn out rate average diameter in the research and actual operation has significant meaning of easing off the combustion calculation and analyzing the combustion situation timely.