Abstract: in order to study the gas adsorption characteristics of anthracite and mudstone reservior under the condition of diferent pressure,the isothermal adsorption experiments,selected N.9 coal seam as experimental samples in Chengzhuang Mine, were done under the condition of 20Cand 2.5 MPa with Co_2、CH_4and O_2.The adsorption constant determination respectively was used. Using Langmuir、BET and D-R modelto fit the experimental data,the results showed that the anthracite adsorption capacity of Co _2 and the mudstone adsorption capacity of 0_2 increased significantly with the pressure increasing,but the anthracite adsorption capacity of 0 2 and the mudstone adsorption capacity of CH 4 were increased not obviously;, the value of D-R model constant D of the adsorption of anthracite and mudstone adsorption of 0 2 was close but theD-R model constant D of CO_2 and CH_4of mudstone were greater than anthracite. t indicated that the aperture distitubute of mudstone was more concentrated than anthracite;The adsorption rate of anthracite on different gas was faster than the mudstone in almost the whole process,but he adsorption rate of coal on diferent gas changed larger than mudstone during the former and the seoond half process. The selective phenomenon of adsorption was more obvious than mudstone and the adsorption rate distribution of mudstone was flat.