In order to solve the drilling problem of mechanical repair to the composite materials, the ultrasonicassisted drilling is researched. First, the mechanism of ultrasonicassisted drilling is studied to both the drill and the cutting edge. Second, the portable ultrasonicassisted drilling system is introduced including the hand drill and the ultrasonic power supply. Third, a design of ultrasonic transducer is analyzed with principle and simulation. The experiments show that by adopting this ultrasonicassisted drilling technique, the drilling flaws, such as laminate, burr, wire drawing, etc., can be decreased compared to the direct drilling without ultrasonic, and simultaneously this method can meet the needs of aircraft battle damage repair (ABDR).