Abstract: Aiming at the coal seam with poor permeability and soft coal quality，the paper put forward a method of increasing permeability combined hydraulic flushing and carbon dioxide cracking blasting. It can further improve the permeability of coal seam and prolong the extraction time of high gas flow. The Field application test research was carried out in a coal mine. It has been found that the drainage gas quantity within 30 days has improved 45% compared to use hydraulic flushing separately. After 60d of drainage, the residual gas content of the area has been reduced by 22%, be relative to drain by using hydraulic flushing alone. It provides reference for gas drainage in soft coal seams of other mining areas.