Roadheaders have been increasingly used in a variety of tunnel cross-sections and roadway excavations. The appropriate setting of key construction parameters of the roadheader can maintain the excellent cutting performance of the roadheader during excavation. In this respect, this paper reviews in detail the previous studies on various experiments and numerical simulations affecting the cutting performance parameters of roadheader. A method for simulating the breaking process during the mechanical cutting of rock was then introduced using the Particle Flow Code in 3 Dimensions (PFC3D). In the numerical simulations, we used the parallel bond model to simulate the studied rock material and completed the calibration of the mesoscopic parameters by numerical simulation tests. In the simulations, we set different cutting modes, cutting depths and cutting thicknesses to study the rock breaking process of the transverse cutter head in a highly weathered granite environment from a microscopic perspective. The simulations indicated that the cutting mode, cutting depth and cutting thickness have significant effects on the cutting force and specific energy consumption. It is feasible to use the available space to the fullest and effectively reduce the wear of the picks by adopting the undercutting mode. The cutting efficiency can be improved and the specific energy consumption of cutting can be significantly decreased by increasing the cutting depth. The optimal cutting depth for highly weathered granite is 13 cm. As the cutting thickness increases, the cutting head’s normal and rolling forces increase linearly, and the cutting efficiency improves. Under the condition of highly weathered granite, the maximum cutting thickness of the Erkat ER1500 transverse cutting head is 12.5 cm. Overall, the results indicate that the discrete element method is a powerful tool for simulating rock cutting process.