Abstract: For the problems of analytical method for gas diffusion of coal particles, we deduce the numerical expression of single diffusion model and propose numerical method of gas diffusion coefficient of coal particles. The difference of result between analytical solution and numerical method is discussed. Result shows that the traditional analytical solution is only suitable for analyzing constant pressure diffusion test result and sphere coal particle, the linear adsorption assumption also runs counter to the real law of gas adsorption. The numerical method considers the real parameters of coal and the external environment, such as adsorption constant, coal porosity and temperature. In this regard, the numerical method can reflect the real diffusion process better. With the same diffusion coefficient, the calculated diffusion ratio by analytical solution is smaller than that of numerical method. If the result of diffusion test on coal particles is used to back-calculate the diffusion coefficient, the analytical method may overestimate the real diffusion coefficient of methane in coal seams.