Abstract: Water jet measures often have good effects on enhancing coal seam permeability,but the effects achieved by different water jet measures vary.To solve the failure mechanism of conventional different water jets on coal seams,two different water jet measures,pulse water jet and hydraulic punching with the same water pressure,are tested on the 9^# coal seam of Xintian Coal Mine in Guizhou.The experimental results show that as the water pressure stabilizes at 20 MPa,the amount of coal punched out by hydraulic punching measure is greater than that punched out by pulse jet measure,and the coal blocks punched out by hydraulic punching are in the form of fine particles,while the coal blocks punched out by pulse jet are in the form of large block sample.The single hole gas flow rate of pulse jet is 1.18 times higher than that of hydraulic punching,and the gas concentration is 13.46% higher than that of hydraulic punching.For the phenomenon of small coal output,the pulse jet presents a fine and regular crack crushing effect on the coal surface,while hydraulic punching presents a chaotic and irregular crack crushing effect on the coal surface.