Abstract: Coal samples from Hexing Coal Mine in Yunnan Province were selected and 8 samples from 1 mm to 3 mm were measured by dynamic image method, each of which was 20 g. The experiment found that the dynamic image method measures the particle size distribution experiment with good repeatability. The minimum diameter of the Ferret and the diameter of the largest inscribed circle are basically the same according to the number of particles. The experimental determination of the particle size distribution of coal sample coal is close to the lognormal distribution, the average particle size is 1 217 μm, and the distribution is left-biased. As the increase of the particle size, the shape of the particle becomes more irregular, resulting in a larger statistical gap depending on the number of particles, the projected area of the particle, and the volume of the particle. The ellipse ratio distribution curve of the coal sample approximates a normal distribution, but the circularity distribution is relatively skewed. As the increase of particle size, the grain shape changes more so that the influence of particle shape should be considered in studying the characteristics of adsorption and desorption of coal samples.