Abstract: In this paper, the isosteric heat of adsorption of the high-rank normal coal and deformed coal were analyzed. Then, the reasons for the deformed coal inducing gas outburst were expressed. The main results are as follows: with the increase of adsorption amount, the adsorption heat of high order normal coal and deformed coal presents a trend of slow increase first and then rapid increase. However, with the increase of gas pressure, the isosteric adsorption heat of coal samples increases at a constant speed. At different adsorption amounts and pressures, the isosteric adsorption heat of normal coal is greater than that of deformed coal. This indicates that the intermolecular forces between the methane molecules and the normal coal surface is greater than that of the deformed coal, and it is easier for the methane molecules to break off from the surface of deformed coal than that of normal coal under the same pressure. The gas migration in deformed coal is mainly controlled by the stage of gas seepage in fractures, so more measures for improving the capacity of seepage should be done for gas control of the deformed coal.