Abstract: In order to study the dynamic response mechanism of the rock fragmentation and its influential factors, from meso-level structure of rock, a numerical model for the rock and shield machine cutters is proposed based on the particle flow code (PFC^2D). The results show that the rock fragmentation process is composed of the cycle of various-small shearings and one large shearing, which causes the cutting force to fluctuate continuously. As the cutter distance increases, the cutting force and rock cracks increase. It shows that the formation of the cracks needs greater forces. From the cutting performance aspect, the positive rake angle of the cutter produces higher cutting efficiency than the negative one. The cutting forces and crack numbers data are statistically analyzed, and the results show that the effect of the cutting depth is greater than the cutting speed.