Kaolinite，as the main adsorbent carrier of clay minerals，cannot be ignored for its contribution to methane adsorption. The double-layer adsorption space model of kaolinite was established in the consideration of the unique 1∶1 double-layer crystal structure of kaolinite. Using the Grand Canonical Monte Carlo method，localized adsorption simulation of single methane molecule in kaolinite supercell and adsorption isothem simulation of methane in kaolinite were carried out to analyze the effects of kaolinite crystal structure，temperature，and moisture content on the adsorption behavior. The results show that the adsorption of methane on kaolinite silico tetrahedron（silicoxylated surface）is stronger than that of Al oxygen eight surface layer（aluminum oxygen hydroxylated surface）. Methane adsorbs on the alkoxylation surface with priority.The adsorbed methane is clustered in the position above the six membered ring hole of silicon tetrahedron and the adsorption with the triangular pyramid configuration is the most stable. The adsorption of methane on kaolinite at 280-400 K is consistent with Langmuir isothermal adsorption type and belongs to physical adsorption. The adsorption capacity and adsorption heat of methane decrease linearly with the increase of temperature. It is confirmed that the adsorption capacity at high temperature can be predicted according to low temperature. Before kaolinite is saturated with water，the presence of water does not change the adsorption trend and the type of methane adsorption，and it only reduce the amount of methane adsorption. When the water content increases from 0 to 20.94%，the adsorption capacity of methane is reduced by 35.06%.