In this study, based on a microwave test, the discrete element program (PFC) is used to establish a microwave-assisted disc cutter rock-breaking model and explore the influence law of the positional relationship between microwave radiation and disc cutter penetration on rock-breaking efficiency, and the results show that: The improvement of the positional relationship has a significant effect on improving the rock-breaking efficiency, and the double-edged cutter reaches and minimum rock-breaking specific energy when breaking the rock in the center position with a waveguide spacing of 90 mm and in the inner and outer positions with a waveguide spacing of 150 mm; When the waveguide spacing is 150mm, the double-edged cutter with cutter spacing of 110mm, 130mm, and 190mm have their advantages in rock-breaking efficiency and economic benefits, which should be selected according to the actual needs of the project. The follow-up research should also fully consider the rock type, microwave parameters, cutter profile, engineering environment, and other factors for in-depth investigation.