In order to study the physical and chemical reaction after CO2 injected into coal beds at different condition.The physical and chemistry reaction among CO2,H2O and coal was studied,and the influence on permeability and porosity of coal beds was carried out.The experimental method was used,so did the basic theory of mineralogy,coal petrology,geochemistry,analytical geochemistry and physical chemistry.In this experiment,the changes of mineral and permeability of coal and water quality were observed through CO2 solution reacting with different coal samples.The differences could be found out by comparing the properties and microcrystalline structure before and after the reaction.There are three results were carried out:First,the content of carbonate in coal beds decreases because of the dissolution reaction between carbonate minerals and CO2 solution,and precipitation is formed by reaction of chlorite and orthoclase.Second,the result that permeability and porosity of coal beds are improved after the reaction is proposed.Third,the initial permeability of different coal samples plays a great role on the reaction,and the improvement of permeability is not obvious in the samples which have too low or too high permeability,and the improvement is good in medium permeability(0.2–3 mD). In order to study the physical and chemical reaction after CO2 injected into coal beds at different conditions. The physical and chemistry reaction among CO2, H2O and coal was studied, and the influence on permeability and porosity of coal beds was carried out. The experimental method was used, so did the basic theory of mineralogy, coal petrology, geochemistry, analytical geochemistry and physical chemistry. In this experiment, the changes of mineral and permeability of coal and water quality were observed through CO2 solution reacting with different coal samples. differences could be found out by comparing the properties and microcrystalline structure before and after the reaction. Here are three results were carried out: First, the content of carbonate in coal beds decreases because of the dissolution reaction between carbonate minerals and CO2 solution, and precipitation is formed by reaction of chlorite and orthoclase. Second, the result that permeability and porosity of coal beds are improved after the reaction is proposed. Third, the initial permeability of different coal samples plays a great role on the reaction, and the improvement of permeability is not obvious in the samples which have too low or too high permeability, and the improvement is good in medium permeability (0.2-3 mD).