Abstract: By means of laboratory gas desorption test of coal particle, the gas desorption rule of coal particle with the same coal sample in three different particle sizes was studied. On the basis of experimental data analysis, combined with theoretical deduction, a mathematical model of gas desorption and diffusion of coal body based on temperature variation was established, relevant validation was carried out, and the applicability of the model was analyzed. The results show that when the adsorption equilibrium pressure is about 0.34 MPa, the gas desorption amount of the coal in three particle sizes can reach 3.77 mL/g, 3.91 mL/g and 5.65 mL/g respectively, there is a negative correlation between desorption rate and particle size. In the process of gas desorption of coal particles, the measured coal body temperature curve takes the shape of "saddle". Under specific conditions, the mathematical model established to describe the initial stage of gas desorption of coal particle can be used to predict the change of coal body gas desorption temperature. It has important reference value for the study of gas migration process and disaster early warning research in coal mine.