Abstract: Underground disposal is one of the most effective measures to reduce CO₂ content in atmosphere to alleviate the greenhouse effect. CO₂ storage in deep unminable coaldbeds shows great potential in China. Taking gas coal as sample in Mazhuang coal mine, Xuzhou, isothermal adsorption experiment was conducted. The result shows that coal adsorption quantity of CO₂ is obviously higher than that of CH₄ under the same conditions (pressure, temperature, coal rank, etc), ratio ranging from 2.68 to 3.36. In the process of adsorption, with pressure increasing, CO₂/CH₄ adsorption quantity ratio is gradually reduced. The equilibrium time of ionic reaction of CO₂ in the coal-bearing water reaches up to about 120 d. With the deep unminable coalbeds in Xuzhou area as research object, the potential of carbon dioxide geologic storage was analyzed and the result reflects that the deep coalbeds in Xuzhou area could be an important site for geologic storage of carbon dioxide in the suitable depth and position.