Abstract: Traditional rock breaking methods such as explosive blasting and mechanical cutting have significant drawbacks, and novel rock breaking technologies such as laser, microwave, and electric pulse have garnered widespread attention. High-voltage electric pulse rock breaking technology demonstrates promising application prospects in fields such as ore pre-fragmentation owing to its advantages of high efficiency, low energy consumption, and environmental friendliness. This technology induces electrical breakdown inside the rock via high-voltage pulses to form plasma channels and achieves rock fragmentation through shock waves and thermal stress, but its fragmentation effectiveness is influenced by multiple factors including voltage and electrode spacing. To reveal the mechanism of high-voltage electric pulse rock breaking and optimize engineering parameters, this paper systematically investigated the effects of peak voltage, electrode spacing, and number of discharges on the fragmentation characteristics and crack propagation patterns of red sandstone through experiments and numerical simulations. The results indicate that voltage dominates the fragmentation mode. As the voltage increases from 96 kV to 120 kV, the number of main cracks evolves from a single radial crack to multiple complex cracks, and the degree of rock fragmentation significantly enhances （from local penetration to overall disintegration）. Electrode spacing influences the fragmentation range; increasing the electrode spacing expands the crack length and width but increases the difficulty of electrical breakdown. At low voltages （≤80 kV）, multiple discharges （≥5 times） are required to accumulate damage, with the failure initiating at the borehole bottom and propagating towards the wall. At high voltages （≥100 kV）, a single discharge can cause the overall failure of the specimen. This paper can provide theoretical support and an experimental basis for the parameter optimization of electric pulse rock breaking technology.