Abstract: Through the permeability test of three different coal samples before and after acidification, the change trend of permeability of each coal sample is analyzed, and then the permeability under different pressures and temperature conditions is tested under different acidification time, and the laws of permeability changing with acidification time, pressure and temperature are obtained. The results show that the permeability of 13^# bituminous coal and 2^# lean coal is better than that of 3# anthracite, that is, the acidification effect of medium and low rank coal is better than that of high rank coal; the influence of confining pressure on permeability is more obvious, with the increase of confining pressure, the permeability shows a decreasing trend; in the early stage of temperature increase, with the increase of temperature, the permeability of different coal samples decreases. In the intermediate stage of acidification, the permeability decreases gradually; in the later stage of temperature increase, the permeability decreases with the increase of temperature, but the change trend is no longer particularly obvious, and gradually enters a stable stage.