Abstract: In view of the difficulty of gas extraction and low drainage efficiency in coal seam of low permeability, based on multi component gas competitive adsorption of CO₂-CH₄, simulation and test for improving seam gas extraction rate through CO₂ injecting CO₂ into coal seam were carried out. A fluid-solid coupling model considering gas-water phases and Klinkenberg effect of CO₂ injection into coal seam for enhancement of gas drainage was established, parameters of gas pressure, gas content and gas extraction rate after coal seam CO₂ injection were analyzed by using COMSOL software and applied in engineering test. The results show that mathematical model of fluid-solid coupling is reliable and reasonable. Gas pressure and gas content in CO₂-injected coal seam decreased faster than those without CO₂ injection. After the field test, the gas concentration increased by 2.02 times and the pure gas extraction volume increased by 3 times. Gas extraction increased after CO₂ had been injected in coal seam, which promotes obviously the gas extraction.