Abstract: In order to investigate the effects of ultrasonic vibration-assisted grinding on cutting force and surface quality of carbon fiber reinforced plastics(CFRP), cutting force model of ultrasonic vibration-assisted grinding was proposed. Theoretical analysis and test verification of trajectory of abrasive particle, the effect of sharped cutting edge, maximum undeformed chip thickness were conducted. The result shows that the cutting force is smaller and the surface quality is better in ultrasonic vibration-assisted grinding than in conventional grinding. The cutting force increases by 44.7% in ultrasonic vibration-assisted grinding when the per-tooth feed rises to 8μm/z from 4μm/z. Meanwhile it is 84.9% in conventional grinding. The cutting force increases by 187.8% in ultrasonic vibration-assisted grinding, which is lower than that in the conventional grinding of 209%, when the cutting depth is high up to 400μm from 200μm. Under the same processing parameters, the resin smearing, surface groove and fiber pull-out substantially decrease in ultrasonic vibration-assisted grinding compared with conventional grinding.