Abstract: For the problems of the low concentration in CBM drainage and the low separation factor in traditional gas separation methods, based on the experiment data of separating CH₄ from low concentration CBM by Taiyuan University of Technology itself, a schematic of purifying mine gas through hydrate is proposed, and a analysis of it's economic application according to thermodynamic equations is analyzed. As the results show that, in initial condition of 0.1 MPa, 293 K, and work condition 1 MPa, 278 K, it needs 0.77 kW·h power to product 1 m³ pure CH₄, in another word say, to get 1 m³ pure CH₄ will spend 0.56 yuan. It is a promising way in economy to separate CH₄ from low concentration mine gas.