The invention relates to a determination method for potential well deep distribution of methane adsorption by coal, which relates to a method for evaluating methane reserves in a coal reservoir, due to characteristic of uneven potential well depth of methane adsorption by raw coal body, multi-measuring point adsorption measurements under adsorption pressure and different constant temperature conditions can be carried out on a block coal sample; by using a Langmuir equation based on adsorption kinetics, the adsorption rate parameter b under different constant temperature conditions and the corresponding temperature T enable fitting calculation to obtain a proportion constant bm, the methane adsorption quantity under each constant temperature condition and adsorption pressure are subjected to segment fitting, quantity of different depths of potential wells can be calculated, and a potential well distribution histogram in a certain depth scope can be drafted. The method can be used for realizing accurate calculation of methane adsorption capability under different temperature and pressure conditions on the coal body, and can be used for accurately evaluating the coal bed gas content of the coal reservoir.