Abstract: Plasma channels are the "tools" for high-voltage pulse discharge to break rock; the formation and expansion of the channels cause the rock crushing process with sharp changes in the impedance of the channels. In order to analyze the energy utilization efficiency of the high voltage pulse discharge rock breaking system, combined with the demolding analysis of rock breaking cavity to obtain the penetration depth and actual length of the channel, a plasma channel impedance model is established based on the energy balance equation. Then a circuit analysis model of the high voltage pulse discharge rock breaking system is established; the simulation and test results show that the model can accurately analyze the output characteristics of the high voltage pulse discharge rock breaking system, which provides theoretical guidance for system optimization.