Abstract: China is relatively rich in coalbed methane.A better estimation of maximum adsorption capacity and recovery ratio is based on a better understanding of isothermal adsorption curve.This paper is going to make a comparative study on Langmuir equation, the representative theory of monolayer adsorption theory, and DR equation, which is based on micropore filling theory on an attempt to find a more suitable model fitting equation.Data of the coal sample from four different coal ranks (R_{o, max} from 0.60% to 3.18%) are fitted.The result shows that V_L and p_L would be more accurate in physical significance and the equation fitting would be more meaningful if the two parameters are calculated before fitted; the accuracy of other parameters is improved while V₀ in DR equation is calculated; and Amankwah method is the most suitable method for calculating p₀ after a comparison of five calculation methods by introducing the concept of virtual saturated vapor pressure.DR equation works better in fitting effect and comes nearer to the actual data after a comparison between Langmuir and DR equation.