Abstract: In order to clarify the mapping law of adsorption capacity, porosity and deformation of gas bearing coal, the influence of adsorption amount on porosity and deformation of coal sample under different gas pressures was analyzed theoretically based on the process of testing isothermal curve of coal adsorbing gas by high pressure volumetric method; the adsorption capacity of gas bearing coal was studied by combining industrial CT technology and high pressure capacity method. The results show that with the increase of adsorbed gas, the porosity of coal gradually decreases and tends to a stable value; the higher the coal metamorphism degree is, the slower the porosity evolution trend is; the volume strain of coal presents approximate linear growth.