In the end face lapping process of photonic crystal fiber, there are many grits cutting narrow walls between the photonic crystal fiber (PCF) air holes. This process is simplified as a single grit cutting single hole wall and finite element method (FEM) is used to establish the numerical simulation model. The formation mechanism of cracks and the influence of different cutting depths and grit tip radii on the processing results are analyzed. The simulation results show that in the cutting process, the edge of hole wall is prone to the collapse area which is distributed along the circumference; the cutting force and collapse area increase with the cutting depth and grit tip radius; for no collapse area generation, the maximum cutting depth of this PCF is about 20nm. This method paves the way for studying end surface processing and coupling application of PCF.