Abstract: Based on the classical theory of active charging of single dust particle, the mathematical model of active charging of dust particle group was established, and the relationship between dust diameter, charging voltage and dust charge mass ratio was obtained. Through the self-developed dust active charge and charge measurement device, the charge mass ratio of dust with different diameters under different charging voltage was studied. The results show that when the diameter of dust particles is from 10 μm to 75 μm, the charge mass ratio of dust particle group decreases with the increase of particle diameter, and increases with the increase of charge voltage. It is consistent with the results of the mathematical model of dust particle group charging.