Abstract: In order to study the coal fracturing effect of high-voltage pulsed water pressure, coal samples which had similar mechanical characteristics to the real C oal seam were prepared.Coal samples were drilled from raw coal and the distribution of cracks in the samples were observed by CT scanning before the test. A high vol tage pulse discharge in water was tested in three axis rigid pressure chamber and CT scan was performed after the experiment.Different effects of high hydrostatic pres sure and high voltage electrical impulses on coal samples under same water pressure were compared. The results showed that the raw coal sample was integral, no obv ious vibration and damage and no obvious cracks. Under condition of 3 MPa hydrostatic pressure, no new fracture was produced at coal sample hole and its surroundin g. Cracks with different lengths and shape swere produced under condition of 3 MPa hydrostatic pressure and 10 k V high-voltage discharge around sample hole.Tests proved that under same water pressure condition, high voltage electrical impulses had better coal seam cracking effect than pure hydraulic fracturing.