This work was based on methane adsorption over four activated carbons with different micropore structures. Applying the more precise D-A adsorption model, the heterogeneity of activated carbon was proved to be initial factor influencing methane adsorption. The correlation between the microporosity and methane adsorption capacity were discussed in detail. The average pore size of activated carbons with unimodal distributed micropores acted as a reflection of fractal dimension. A linear relationship between surface area and methane adsorption capacity were revealed, indicating monolayer adsorption model of methane on activated carbon. The surface area, as an available microstructure parameter, can be applied as a direct index for estimating the methane adsorption over serious of activated carbons. (C) 2014 Elsevier Ltd. All rights reserved.