Abstract: According to the characteristics of high gas and low permeability of No.2 coal seam in Xiaohuigou Mine, in the 2204 working face of Xiaohuigou Mine, the acidizing and permeability increasing technology of coal seam is studied. The test results show that the microscopic pore structure of No.2 coal seam is relatively complex, and the tortuous degree of micropores and small holes is high, which is beneficial to gas storage, and the mineral composition is mainly SiO2, Al2O3, TFe, CaO and MgO. According to the mechanism of acidizing and permeability increasing of coal seam that has been mastered, the EGF acidizing and permeable materials suitable for No.2 coal seam are ammonium hydrogen fluoride（5%）, KCl（２％）, citric acid（８％）, sulfamic acid （7%）, catalyst（1.5%）, C7H13NO4S（0.8%）, EDTA（0.5%）, and KMS-6（l%）. The results show that the maximum volume fraction of gas extraction in single hole is 68.2%, and the volume fraction of gas extraction in single hole is increased by 1.22-25 times. After acidification, the gas mixing flow in single hole was increased by 7.17-11.75 times. The gas content in the test area decreased by 18.68%-25.91%. Compared with other permeability increasing methods, it has the advantages of simple construction, strong universality and remarkable effect, and solves the problem of difficult gas drainage in Xiaohuigou coal seam with high gas and low permeability.