Abstract: Carbon fiber reinforced plastics (CFRP) is a woven material, which has the characteristics of anisotropy and high strength. It is difficult to process and has poor processing quality. In view of this situation, the electroplated diamond nesting drill was used to carry out comparative experiments between ultrasonic assisted drilling and conventional drilling on CFRP. Through the analysis of the quality of the entrance and the inner wall, the influence of the ultrasonic vibration on the quality of the entrance and the inner wall of the hole was studied. The results demonstrate that compared to conventional drilling, the glitch and delamination at the entrance of hole were significantly reduced, and the machining defects on the inner wall of hole were also improved.