Abstract: With the references of the successful mode of the surface hydraulic fracturing technology, the mechanism of the hydraulic fracturing and permeability im proved gas drainage in the underground mine was studied.According to the features of the single and low permeability high outburst seam, a completed set technology and equipment of the fracturing and permeability improved gas drainage in underground mine was researched and developed.A industrial trial on the technology and eq uipment was conducted.The applied results showed that with the hydraulic fracturing of the seam coal in the underground mine, the seam permeability of No.24110 coal mining face in No.10 Mine of Zhongping Energy Company was improved by 800 times, the gas drainage value of a single borehole was improved by 120 times.After hyd raulic fracturing, the coal and gas outburst test indexes were dramatically reduced during heading of No.2115 transportation roadway in No.6 Mine of Hebi Coal compan y.The gas volume fraction was reduced to below critical value 0.8%.The danger of the coal and gas outburst was highly reduced.