Abstract: In order to quantitatively calculate a ftting degree of the historical ftting results of the coalbed methane well gas production, based on a set pair analysis principle as a theoretical base, a mathematic model to calculate a ftting degree between a historical ftting curve of the coalbed methane well and the actual production curve was established. Based on the historical ftting achievement of the gas production quantity from two coalbed methane wells in Qinshui Basin as a study object, a calculation was conducted on the fiting degree and the fiting curve effect was judged. The calculation results showed that the established mathematic model could eas ily calculate the ftting degree of the ftting curve and could accurately select a best ftting effect curve. The ftting effect of No.1 well was good, the ftting degree was 8 4.3% and the ftting parameters could be the parameters of late exploration and development. The ftting effect of No.2 well was poor, the ftting degree was 71. 2% an d the ftting parameters should be considered with the actual evaluation standards for the application.