Abstract: In order to reveal the coal and rock structure variation law under the joint role of the stress and gas adsorption, a CT scanning was conducted on the coaI samples under the conditions of the different axial loading and different gas pressures. Based on the CT images, the voxel porosity a was defined and the volume strai n of the coal samples, CT image grey scale and pore distribution variation law were analyzed. the results showed that the voxel porosity a could reflect the different siz e pore structure variation within the coal samples under the joint role of the stress and gas adsorption. When 0 < as 20%, the voxel region in the gas role would play a | eading role. When a > 40%, the voxel region would mainly play a role of gas migration channel. Gas adsorption would firstly occur in the 0 < a S10% voxel region and w ith the axial pressure increased, the adsorption would steadily play a role to the 10% < as20% voxel region. Compared to the gas adsorption, the stress would have a C hange role to the pore structure of the coal samples remarkably.