To quantitatively analyze the dynamic response characteristics of prefabricated fractured rock mass under the coupled action of impact load and confining pressure, a SHPB numerical model was established using ANSYS/LS-DYNA based on one-dimensional stress wave theory and the HJC dynamic damage constitutive model. Dynamic impact simulations were carried out on prismatic marble specimens with different prefabricated fracture inclination angles and different initial confining pressures. The results show that under a given strain rate, the pre-peak segments of the stress-strain curves for various working conditions are basically coincident, and macroscopic cracking mainly occurs in the short duration near the peak stress. Confining pressure has a significant enhancement effect on the dynamic strength. The peak stress increases with the increase of confining pressure, and its increase with the variation of fracture inclination angle is more significant under high confining pressure. When the confining pressure is 0, 5 and 10 MPa, the increase of peak stress with the variation of fracture inclination angle is approximately 14%, 20% and 30%, respectively. The peak strain of the rock mass increases from about 0.004 to about 0.006 1. The crack morphology is generally dominated by "X"-type shear failure. Based on the crack propagation trajectory and the crack initiation mechanism, five typical crack types and one fragmentation characteristic can be summarized. As the confining pressure increases, the crack network inside the rock mass becomes more complex and the fragmentation degree of the specimen intensifies significantly. Energy evolution analysis shows that when the incident energy is kept consistent across all working conditions, as the confining pressure increases from 0 to 10 MPa, the average energy absorption rate of the specimen increases from 6.13% to 9.35%, the energy reflection rate decreases from 93.54% to 89.99%, and the energy transmission rate increases from 0.33% to 0.66%. The dissipated energy generally increases with the increase of confining pressure. As the fracture inclination angle increases, the dissipated energy shows a local low value near 45° and then increases rapidly. The research results can provide a reference for damage assessment and stability control of fractured rock mass under the coupled action of blasting vibration disturbance and in-situ stress in scenarios such as shallow slopes and deep roadways.