Triboelectrification in an insulative granular system is a common natural phenomenon, but until now it has not been well understood. The space on the moon or Mars is suffused by a large amount of fine dust. These tiny dust particles are so adhesive that they can easily stick to any exposed surfaces, which may provoke serious problems, such as reducing the efficiency of solar panels, and resulting in the thermal control failure and the false instrument readings. In recent years, dust removal by using an electrodynamic field is considered as an effective method to mitigate dust pollution. Research shows that the triboelectrification on the particle surface contributes most to the electrostatic source of lunar dust. Consequently, the study of the mechanism of triboelectrification is very important in removing dust particles. In this paper, an analytical model based on the high-energy electron hypothesis is developed to predict the triboelectric charge distribution among particles. The particle size dependence of the tribo-charge is obtained, and the influence of the size range on the tribo-charge probability is also demonstrated. An upper limit for the charge distribution is revealed, and its possible cause is discussed. The particle dynamics simulation is carried out to investigate the charge transfer during particle collisions, thereby verifying the prediction results obtained by theoretical analysis.