Based on tunnel boring machine (TBM) disc cutter penetration laboratory model tests, the penetration load evolution characteristics of high-strength granite specimens under different confining pressures were studied using three different rock-breaking modes (intact rock-breaking, rock breaking along pre-cutting trajectory and rock breaking between pre-cutting trajectory). The study focused on revealing the penetration load-penetration depth characteristic curves, peak load, maximum drop amplitude variation laws, and obtaining the force characteristics of TBM disc cutters under different rock-breaking modes and confining pressures. The results show that: (1) The penetration load-penetration depth characteristic curve of the high confining pressure group drops earlier and has a smaller decrease in amplitude than that of the low confining pressure group, but the corresponding penetration load is not the peak load, while the initial drop load of the low confining pressure group is the peak load, and the drop amplitude is larger; (2) The peak load and the maximum drop amplitude of the penetration load are smallest at medium-high confining pressures of 10-15 MPa, indicating that this confining pressure range is more conducive to TBM excavation; (3) Under low confining pressure conditions, choosing rock-breaking between pre-cutting trajectory mode can reduce TBM disc cutter penetration load more effectively than rock-breaking along pre-cutting trajectory mode. However, the rock sample with the rock-breaking along pre-cutting trajectory mode exhibits wedge failure, and its maximum drop amplitude is the smallest, which can reduce the impact load on cutters and reduce cutter wear.