Abstract: For aimed at the gas drainage problems of the low permeability coal seam, we proposed the method of the static expansing expansion and cracking technology to increase the permeability coefficient of the outburst coal seam. According to the static expansing expansion and cracking active principle: that after the expanded rock will experience three processes of the crack initiation, crack dissemination and crack extend through, a large number of new fractures in rock mass can greatly improve their gas permeability coefficient. The experiments proved thate static expansion agent can expand and crack the coal and its roofbottom and floortop beds. The experiments demonstrated the active principle and feasibility of improving the permeability coefficient by the static expansing expansion agent. The expansion performance is effected by the operation temperature, the hole diameter, the expansion agent concentration and so on. In underground work environments of the coal mine, the expansive force of four types of static expansion agent all can reach up 30 to 50 MPa. Through arranging the free surfaces reasonably, the static expansion agent can expand and crack the coal rock mass to increase their gas permeability coefficient by a lot of new fractures.