Abstract: In order to study the accuracy of commonly used desorption formulas in describing the gas desorption law of mixed particle coal samples, based on the adsorption and desorption experiments of mixed particle coal and gas under different adsorption pressures, Matlab software was used to fit the correlation coefficient and diffusion coefficient of each desorption formula in different adsorption pressures and time periods, and the fitting results were discussed and analyzed. The results show that the gas desorption amount and initial desorption velocity of mixed particle coal samples increase with the increase of adsorption pressure. The desorption law is suitable for Qin Yueping type, Winter type and Sun Chongxu type, but weak for Bolt type and Barrer type. When the adsorption pressure increases, the correlation coefficient of partial desorption formula also increases, and the diffusion coefficient of different formulas has a significant change trend. As the desorption time goes on, the correlation coefficient of partial desorption formula decreases.