According to the problems of gas drainage in rock cross-cut coal uncovering on high gassy coal seam with low gas permeability coal seam, a novel technology which uses high pressure water jet to slot coal seam is presented to raise the methane drainage radius and permeability. Based on the distribution of water jet velocity, the relationship of impact force of water jet and characters of coal is analyzed. Besides, the velocity of coal partial basing on the relationship of force of partial and dip of drilling is studied. Then, the effective diameters of slotting are calculated. Finally, the novel technology is applied to the Pingdingshan mine. The results show that quantities is decreased 38.2%，gas drainage rate is increased 2.86 times and the period of gas drainage is reduced 57.1% and the area of the gas drainage is widened 2.05 times compared to original technology.