Abstract: Based on the multi-layer assumption of gas adsorption in coal, the multi-layer adsorption theory of gas in coal is deduced, with this theory, the test laws of gas adsorption are fitted, and the theoretical analysis are carried out. The results show that the multi-layer adsorption theory of gas is well fitted by gas adsorption isotherm, and the fitting correlation can reach more than 0.99. On the surface of coal body, the gas monolayer adsorption volume Vm increases linearly with temperature decreasing. The difference value of adsorption heat Q and gas condensation heat QL is linear correlation with temperature T. The number of gas adsorption layers on coal surface increases linearly with temperature decreasing.