Abstract: In order to study the adsorption features of the coal sample before and after the acidation,the coal of Yibin Baijiao Mine was taken as the main study object, an acidation and deashing treatment were conducted on the partial coal particles from the grinding and screening and the coal pores was characterizationed.The methane adsorption features under the reservoir temperature was explored by isotherm adsorption test.The test results showed that after the acidation and deashing conducted, the specific surface area and the pore volume of the sample were increased. Due to the acidation treatment, the minerals or impurities within the coal samples would be removed, the pore diameter could be increased and the pore area and pore number could be increased. In the isotherm adsorption test, the balance adsorption volume of the coal sample YB2 with the acidation treatment would be obviously higher than the coal sample YB1 with no acidation treatment. The adsorption potential theory was applied to explore the pore structure variation under a certain reservoir temperature highly affected to the coal adsorption gas.