There were some problems in the ordinary cutting （OC） process of carbon fiber reinforced resin matrix composites， such as excessive cutting force， poor surface quality and serious under surface damage. In order to improve the above problems， this paper proposed to use ultrasonic vibration assisted cutting processed CFRP. The cutting force and subsurface damage depth were studied through simulation analysis. The results show that machining CFRP with UVC can reduce the cutting force by 13%~80%， and the fiber direction angle has little effect on the cutting force. Compared with OC， UVC processing CFRP with 0° and 45° fiber direction angle can reduce the depth of subsurface damage by appoximately 50%； When processing CFRP with 90° and 135° fiber direction angle， although the damage depth under the surface is not improved，a relatively flat machined surface and small damage area are obtained.