Abstract: Two kinds of biomass activated carbon（AC） were synthesized from wheat straw （WS） and corn straw（CS） in the laboratory, which were evaluated as selective adsorbents for the separation of CH4 from CH₄/N₂ mixtures. Adsorption isotherms of the pure gases （N₂ and CH₄） were performed at three different temperatures（303, 323 and 343 K） and SIPS model was used to analyze its correlation. The ideal adsorbed solution theory（IAST） was applied to predict the binary adsorption equilibrium. The isothermal heat of adsorption was estimated from the pure component adsorption data by means of the Clausius-Clapeyron equation and the SIPS equation. All the adsorption equilibrium parameters were integrated into one performance index, and the adsorbents were evaluated in terms of gas adsorption separation factor, draft performance and equal heat of adsorption, so as to select the most suitable adsorbents under the conditions related to specific applications.