Abstract: A scanning electron microscope was used to observe the microstructure of the hole surfaces drilled on CFRP samples. SEM micrographs showed that some areas of the hole surface were covered with polymer while others were dominated by broken fibers. The latter increased with the increase of cutting speed. The roughness of the drilled surface also varied. The roughest parts located at the points where the fibers were fractured owing to bending shearing stresses. The broken face of each fiber was basically perpendicular to its own axis though the fibers broken by shearing appeared different with those by bending.