Abstract: [Objective]The purpose of this paper is to explore the fracture propagation mechanism of rock mass under the action of high-voltage electrical pulses. [Methods]Based on the theories of fracture mechanics and damage mechanics, using the phase field method and with the aid of numerical simulation software, the evolution law of the initial fractures of rock mass under the action of high-voltage electrical pulses was studied. And the incremental change of the fracture length of rock mass and the damage evolution trend inside the rock mass were quantitatively analyzed.[Results] The research results showed that the damage condition of rock mass was closely related to the intensity of shock waves and their variation rate. The greater the intensity of the shock wave and the faster the rate of change, the faster the expansion speed of the crack, and the extent and range of damage to the rock also intensified accordingly. The rock-breaking efficiency of the electrical pulse rock-breaking system was positively correlated with the discharge voltage and energy storage capacitance, negatively correlated with the length of the plasma channel, and had a weak correlation with the loop inductance. The displacement at the rock-breaking point of high-voltage electrical pulse due to disturbance was similar to the pressure waveform of the shock wave. Moreover, due to the complex structure of the rock mass and the characteristics of plastic deformation, the growth of the internal displacement of the rock mass will showed a certain lag compared with the propagation of the shock wave and the change of pressure. [Conclusion]The research results provide a new perspective for characterizing the growth amount of fractures and the damage amount of rock mass in high-voltage electrical pulse rock breaking, and facilitate the reasonable adjustment of parameters of engineering rock breaking equipment.