In this paper,the adsorption isotherms of CH₄ and CO₂ on MIL-101 were obtained by means of the gravi-metric method at 298,303,308 and 313K,and the corresponding isosteric adsorption heat was estimated.Then,the pure gas adsorption was calculated by using the DL- IAST model,and the adsorption selectivity of CO₂ on MIL-101was discussed.The results show that (1) the adsorption capacity of pure CO₂ on MIL-101 is up to 14.51mmol/g at298K and 2500kPa,which is much higher than that on activated carbon,zeolite and molecular sieve under similarconditions; (2) the isotherms of pure CO₂ and CH₄ well accord with the Double- Langmuir model,which shows thepresence of two adsorption sites; (3) the isosteric adsorption heat of CO₂ on MIL-101 ranges from 19,3 to 25,5kJ/mol;(4) as compared with CH ₄ ,CO₂ is of higher surface free energy for its interaction with the framework of MIL-101;(5) the adsorption selectivity index of CO₂ over CH₄ on MIL-101 is up to 5.6 at 298K and 250kPa; and (6) theadsorption selectivity of CO₂ over CH₄ gradually decreases with the increase of pressure and the concentration of CO₂ in CH₄ /CO₂ mixture.