Carbon dioxide injection in coal seams is known to improve the methane production of the coal seam, while ensuring a safe and long-term carbon sequestration. This improvement is due to the preferential adsorption of CO2 in coal with respect to CH4: an injection of CO2 thus results in a desorption of CH4. Gas extraction proceeds by desorption from the coal material and by convective transport through a set of small natural fractures (cleats), which are typically spaced by a few centimeters. Most of the permeability of the coal reservoir comes from the cleat network, but the permeability of those cleats strongly depends on the underground stress. Actually, in the real life you will see that coal mostly related with humidity. That's mean it've a composition of H2O too, So we need to study more about H2O.We want to know that how water have an effect to suction methane process.