Abstract: The hole edge collapse defects in drilling medium and high volume ratio silicon carbide particle reinforced aluminum matrix composites (SiCp/Al) were observed by 3D test and statistically summarized, the defect mathematics model of edge collapse was established and a geometric method based on edge collapse volume has been presented to evaluate edge collapse level. The results show that the main defects in drilling SiCp/Al composites are edge collapse defects which are mainly produced at the exit of hole. The evaluation method is objective and real to evaluate the edge collapse defect level under different parameters in drilling SiCp/Al composites, and it has a certain guiding significance to process parameters optimization.