To address the problem that the fracturing effect of the combined high-voltage electric pulse-hydraulic fracturing technology is limited when encountering cemented natural fractures, based on the energy release rate theory, a fluid-solid coupling model for rock breaking by the combined high-voltage electric pulse-hydraulic fracturing, which incorporates cemented natural fractures, was established. Considering the interaction between cemented natural fractures and hydraulic fractures, the effects of different principal stress differences, intersection angles between hydraulic fractures and natural fractures, and voltage on fracture propagation were studied. The results demonstrate that under conditions of principal stress difference less than 10 MPa and intersection angle less than 30°, high-voltage electric pulse fracturing increases fracture width by approximately 25% compared to conventional hydraulic fracturing. At low principal stress differences, hydraulic fractures propagate along natural fractures, while at high principal stress differences, they penetrate through natural fractures and extend in the direction of maximum principal stress. When the intersection angle is small, natural fractures are more readily activated and extend along their original orientation. Within a voltage range of 1～5 kV, the total fracture width increase reaches approximately 94%, with natural fractures becoming significantly more susceptible to activation. These findings provide theoretical foundation and technical guidance for applying high-voltage electric pulse and hydraulic fracturing technology in practical engineering to enhance resource extraction efficiency in complex subsurface formations.