Abstract: By studying the evolution law of coal pore structure under the action of long-term gas atmosphere, this paper qualitatively describes the pore evolution characteristics of coke coal after long-term adsorption of gas, and gives guidance for micro-environmental aspects of coalbed methane mining and coal mine gas safety. The pore structure of coking coal is characterized by high pressure mercury injection test and SEM. After measuring the adsorption gas N2, the Shanxi coking coal sample was compared with the original coking coal sample: the specific surface area of the hole increased by 27.8%; the pore volume decreased by 10.6%. After the non-adsorbing gas He acts, the Shanxi coking coal sample is compared with the original coking coal sample: the specific surface area of the hole is reduced by 21.9%, and the pore volume is increased by 76.6%. The results show that the adsorptive gas mainly affects micro-pores and pores; non-adsorbed gases mainly affect meso-pores, macro-pores and visible pores. The adsorption of the adsorptive gas will reduce the pore expansion of the pores to a certain extent.