Considering the various influencing factors of enrichment of coal bed methane, the evaluation indexes of enrichment for coal bed methane are determined. The weight values of all factors indexes are given and the fuzzy mathematics model is established on the basis of the fuzzy mathematics. As a case study, the fuzzy mathematics model is applied to the assessment of enrichment of coal bed methane. The results show that the No.5 coal seam of Shan 2 of Shanxi formation in Daning-Jixian is a better enrichment area. The evaluation result performed on the basis of the fuzzy mathematics model is in good agreement with the measured result. The example indicates that the method is credible and has high precise. The assessment system established in the paper can be regarded as a reference model in coal bed methane exploitation potential assessment.