Studying the law of coal adsorption capacity under the action of liquid nitrogen is very important for the extraction of coalbed methane. For this study, the lignite's ability to adsorb methane was studied after it had been frozen by a number of different freezing techniques. In addition, the changes in the organic functional groups on the coal after freezing were identified by using infrared spectroscopy. The results demonstrate that as the duration of liquid nitrogen freezing and the number of freezing cycles increase, the lignite's gas adsorption capacity first decreases, then increases, and finally maintains a stable value. As the liquid nitrogen freezing time increases, the proportion of oxygen-containing functional groups increases, but the percentages of substituted benzene groups and aliphatic hydrocarbon functional groups decrease. The research shows that, compared with a single freezing, cyclic freezing has a greater effect on the lignite's gas adsorption capacity. Freezing influences the proportion of the substituted benzene functional groups on the coal the most; after freezing, the rates of change in the proportions of aliphatic hydrocarbon and oxygen-containing functional groups are only 70.76% and 80.29% as large as the change in the substituted benzene functional groups. As the proportions of the three types of functional groups increase, the lignite's gas adsorption capacity first decreases but then increases. This study will promote the development of liquid nitrogen freezing technology for coalbed methane extraction.