Changcun Mine is a high gas mine， the No.3 coal seam with poor permeability. In order to effectively increase the permeability of No.3 coal seam and improve gas drainage effect， permeability measures must be taken to solve Low permeability of the coal seam. Study of hydraulic cutting seam in low permeability No. 3 coal seam was carried out， drilling parameters and their arrangement on experiment site were settled. The study showed that hydraulic cutting seam permeability improvement technology improved the gas drainage quantity by 3～3.75 times， high concentrations of drainage time extended to 1.2 times， the technology got good effect of gas drainage.