The mechanism of nano-grinding of single crystal silicon carbide (SiC) with lattice defects is not very clear. A molecular dynamics simulation system was used to study the nano-scratching mechanism of single crystal silicon carbide (SiC) with lattice defects. The simulation model including diamond abrasive grains and 4H-SiC workpieces with different lattice defects has been built. The simulation results reveal the effects of different defect types on key parameters such as interatomic potential energy, temperature, stress and machining performance. It is found that vacancy defects lead to unstable interatomic potential energy of the workpiece, resulting in increasing the temperature of the workpiece up to 42 K after scribing, while dislocation defects show relative stability. During nano-scrubbing, crystals with dislocation defects exhibit the highest average paradigm equivalent stress of 5.29 GPa, while crystals with vacancy defects exhibit the lowest stress of 5.07 GPa, which suggests that vacancy defects reduce the yield strength and favour the removal of atoms, whereas dislocation defects increase the yield strength and impede the removal of atoms. Furthermore, vacancy defects inhibited dislocation nucleation and reduced the thickness of the damage layer, whereas dislocation defects led to significant dislocation formation and a deeper damage layer.