Abstract: In order to study the separation characteristics of coalbed methane on carbon molecular sieve (CMS) which is depend on the effect of kinetics,the adsorption kinetics data and equilibrium isotherms of CH4 ,N2 and O2 on two kinds of CMS ( CMS - 1, CMS - 2) were measured and modeled. The results show that the equilibrium adsorption amounts of CH4 greater than N2 and O2 on the two kinds of CMS;the micro pore diffusion model can forecast the ad- sorption kinetics of CH4 ,N2 and O2 on CMS well;The diffusion rates of CH4 ,N2 and O2 were fast when F is less than Fc which were 0. 5,0. 6 and 0. 7,and after that the diffusion rates drop obviously. On the two kinds of CMS,the com- prehensive selectivity of N2 and O2 or CH4 are 5. 84,18. 75,4. 20 and 16. 82 which indicate that the two kinds of CMS could be used to enrich CH4 from coalbed methane.