Abstract: In order to explore the influence of prefabricated cracks on coal rock mass induced by high voltage electric pulse in water, and improve the permeability of coal and rock strata in the mining area, the high voltage pulse cracking tests were carried out on similar samples of coal and rock mass with and without prefabricated cracks. On this basis, PFC numerical simulation software was used to build coal and rock mass models with and without prefabricated cracks under different peak pressures for fracture simulation. The experimental and simulation results show that the prefabricated cracks have a certain promoting effect on the fractured coal and rock mass caused by high pressure pulse discharge. The prefabricated crack has a certain guiding effect on the crack propagation, but the crack propagates along the direction parallel to the maximum principal stress. With the increase of the peak pressure, the crack network formed next to the prefabricated crack develops more fully, the crack length extending outward along the end of the prefabricated crack decreases, and the difference between the number of force chain fractures and those without the prefabricated crack also decreases.