Abstract: For the issue of low gas drainage rate in coalbed gas development and mine safety production, a method of coal seam permeability improvement with high-pressure pulse discharge in water was proposed. First, the electrohydraulic effect and mechanism of water-shock wave in electric pulse discharge process were analyzed. Then, the mechanisms of coal seam cracks and crack propagation were studied. Finally, a set of experimental system with high-pressure pulse discharge was built, and the coal seam permeability improvement test of high-pressure pulse discharge was carried out. The experimental results show that method can effectively change the pore and fracture structure of coal seam, and can improve the coal seam gas permeability, and has certain feasibility and superiority in seam permeability improvement.