Abstract: In order to understand the influence of linear regression equation on gas adsorption constants, isothermal adsorption test of four kinds of coal samples was tested by volumetric method. Adsorption constants were fitted to data by four kinds of linear regression equations including Lineweaver-Burk, Eadie-Hofstee, Scatchard and Langmuir. The difference of adsorption capacity was compared and analyzed between experiment and calculation from the different adsorption constants. The results show that the Lineweaver-Burk equation is the best in the calculation process of adsorption constant according to correlative coefficients of linear regression; all the linear regression equations have a consistent variation trend of adsorption capacity error rate, and the curves is a skewed distribution; different equations of linear regression is applied to different ranges of adsorption pressure due to absolute error rate.