Abstract: In order to study the relationship between coal permeability and gas pressure gradient, a mathematical model of coal permeability and gas pressure gradient is established in consideration of the coal body adsorption deformation, and the seepage experiment was carried out under the condition of constant temperature. The seepage experiment of coal samples were carried out under condition of different adsorption equilibrium pressures with the same pressure gradient and the same adsorption equilibrium pressure with different pressure gradients. Research results show that:Under the condition of lower pore pressure, the permeability of coal decreases with the increase of adsorption equilibrium pressure; the dynamic evolution model of permeability well describes the gas flow pattern in the coal seam gas drainage process. The research results can provide some theoretical support for the coal mine gas control and drainage work, which has certain guiding and practical significance.