Abstract: Plasma rock breaking technology has the characteristics of being green, efficient, and controllable, and has great application prospects in deep rock breaking. This article conducted four sets of plasma sandstone blasting experiments under different confining pressures. Through CT scanning and 3D reconstruction, the morphology, structure, and distribution of internal fractures in rocks were compared and analyzed. The rock breaking effect of plasma rock breaking technology under different confining pressures was studied. LS-DYNA was used for numerical simulation to explore the mechanism of plasma rock breaking under different confining pressures and the expansion of internal fractures in rocks during blasting Distribution and damage evolution patterns. The results show that under the same voltage, as the three-dimensional confining pressure increases, the number and distribution range of surface cracks on the rock gradually decrease. The complexity and connectivity of internal cracks in sandstone significantly decrease. Secondly, in the dynamic stress field generated by plasma blasting and the static stress coupling field generated by confining pressure, the shock wave generated by plasma blasting has a greater effect in the initial stage of the explosion, There is no significant difference in the crack morphology and central expansion area of rocks under different confining pressures. As the shock wave attenuates, confining pressure plays a decisive role in the later stage of plasma blasting, inhibiting the crack propagation and damage evolution of the rock