In order to investigate the influence mechanism of effective stress on the adsorption property of coal

a series of isothermal adsorption experiments of coal from Lu’an coal mine are designed and conducted. Combining the porosity and pore size distribution law determined by mercury injection test and using the self-made testing apparatus

the difference of methane adsorption law are confirmed under the different effective stress conditions. The results show that: ①When temperature is constant

CH4 adsorption amount decreases as the effective stress increases; and the larger the gas pressure is the stronger such change tendency becomes. ②The Langmuir equation constant a has a negative correlation with effective stress and the constant b has a positive correlation with effective stress. It is related to the closure of a portion of micropores and the change of chemical potential difference. ③According to the fitting results of experiments

the Langmuir equation takes the influence of effective stress into account is proposed. The research results have some reference significance to the reservoir evaluation and development of coalbed methane.