Abstract: The mechanism is elaborated that the fracturing increasing permeability caused by biaxial tension mohaupt blasting in deep holes of coal seam. In Xinfeng Coal Mine, the comparative experiments of gas drainage effect are carried out in deep holes of coal seam by biaxial tension mohaupt blasting, the practice indicates that the biaxial tension mohaupt blasting technology can fracture coal body more effectively, increase permeability and improve gas permeability of coal body, which provides a guarantee for safety production of coalmine. Through this technology, the concentration, flow and scalar have increased dramatically in surrounding drainage holes. After two days, the values reach maximum, then the attenuation occurs but still higher than the data before blasting. The gas scalar is the most, which is considered as the best index to measure drainage effect, it is indicated that the coal seam permeability can be increased indeed by mohaupt blasting.