Rock damage is one of the key factors in the design and model choice of the mining machinery. In this paper, the influence of rock damage on rock fragmentation and cutting performance was studied using PFC2D. In PFC2D software, it is feasible to get rock models with different damage factors by reducing the effective modulus, tensile and shear strength of bond by using the proportional factors. A linear relationship was obtained between the proportion factor and damage factor. Furthermore, numerical simulations of rock cutting with different damage factors were carried out. The results show that with the increase of damage factor, the rock cutting failure mode changes from tensile failure to brittle failure, accompanied by the propagation of macro crack, the formation of large debris and a notable decrease in the peak cutting force. The mean cutting force is negatively correlated with the damage factor. Besides, the instability of cutting force was evaluated by the fluctuation index (FI) and the pulse number (PN) of unit displacement. It is found that the cutting force is quite stable when the damage factor is 0.3, which facilitates the reliability of cutting machines. Finally, the cutting energy consumption of rock cutting with different damage factors was analyzed. The results reveal that the increase of damage factor can raise the rock cutting efficiency. The aforementioned findings play a significant role in the development of assisted rock-breaking technologies and the design of cutting head layout of mining machinery.