In this paper, to obtain the mechanism of the effect of infrared radiation heating on the adsorption of methane by coal, experiments were combined with derivations, calculations of theoretical derivation、calculation of thermodynamic parameters and observations of microstructure, to provide a reference for infrared radiation heating increased coalbed methane production technology, to provide a reference for the application of infrared radiation heating to increase production of coalbed methane(CBM).Based on adsorption experiments, the variation in the saturation adsorption amount a and adsorption equilibrium constant b in the Langmuir equation were investigated, and the value of b was supplemented by a theoretical derivation. The results showed that (1) The amount of methane gas adsorbed by coal increased with increasing equilibrium pressure and decreased with increasing power of the infrared radiation source during infrared radiation heating. (2) The adsorption equilibrium constant b is exponentially related to the power of the infrared radiation emitting device. As the IR radiation power increased, the b value decreased, and the adsorption capacity of coal decreased. (3) The standard Gibbs free energy of two coal samples during the adsorption process was ΔG0<0, which indicated that all the adsorption processes were spontaneous. The values of the standard enthalpy change of adsorption ΔH0 were − 32.432 kJ/mol and − 29.614 kJ/mol, which indicated that the adsorption of methane in the coal seam was physical. The standard adsorption entropy changes ΔS0 were − 0.078 kJ/mol and − 0.069 kJ/mol, respectively, meaning that the adsorption process system decreased the entropy. Both ΔH0 and ΔS0 were less than 0, which showed that the absorption of methane gas on coal was spontaneous at low temperature. The magnitude of the value of the equivalent heat of adsorption qst was positively correlated with the amount of methane adsorbed, i.e., the adsorption of methane gas by coal samples was a continuous exothermic process.