Abstract: The permeability of coal seam in China is generally low, it leads to high difficulty of gas drainage, low extraction rate, and large amount of drill engineering. In depth, the permeability of seam is much lower under high stress condition, and the difficulty of gas drainage is increased. Relieving stress and improving permeability is the key to the gas disaster prevention and efficient coalbed methane exploitation of low permeability seam in deep mine. Water jet cutting technology is one of the important technologies of coal seam permeability improving. In the paper, the current research status of hydraulic slotting technology, including pressure relief and permeability improving mechanism, strengthening jet method, slotting technique and equipment, is reviewed. Furthermore, the current problems faced in hydraulic slotting technology development, such as quantitative mechanism of permeability increasing, process method, effect evaluation method, and equipment capability, are analyzed. At last, development trends of the capability of cutting, direction of equipment development, and the application prospect of hydraulic slotting technology are overlooked.