Abstract: Taking four different metamorphic degree coal samples as the study objects, based on basic parameters and different temperature adsorption experimen ts, the paper used the Langmuir adsorption dynamics equations and thermodynamic theory to build three-dimensional calculation models of change value of surface fre e energy and isosteric heat of adsorption respectively. Then adsorption capacity and adsorption thermodynamic characteristics of different metamorphic degree coals w ere analyzed. The results showed that the change value of surface free energy increased rapidly with increasing pressure at first while increased very slowly at last, ho wever, it would decrease with increasing temperature. The change value of surface free energy from large to small in order was coking coal, fat coal, long-flame coal, a nthracite coal, and the adsorption capacity of per unit area was also in this order. The trends of specific surface area and adsorption capacity were both in U type in ord er that anthracite coal, long-flame coal, fat coal, coking coal, so the specific surface area was the main factor which influenced the adsorption capacity of different meta morphic degree coals. The isosteric heat of adsorption increased with increasing adsorption volume and temperature respectively, and the initial isosteric heat of adsor ption increased with increasing metamorphic degree of coals in order that anthracite coal, coking coal, fat coal, long-flame coal.