Abstract: The relationship between the ultrasonic grinding surface quality of Al2O3-ZrO2 nano-composite ceramics and the ultrasonic grinding frequencies was researched. Based on the ultrasonic singlepoint scratching test, the change of material removing style illustrates the improvement of surface quality with ultrasonic grinding. The reduced equivalent rigidity of the surface under ultrasonic vibration leads to a removal mode transition from brittle to ductile. And this phenomenon becomes more evident as frequency increases. The research shows that, the surface quality with ultrasonic vibration is superior to that without ultrasonic vibration, and the increasing frequency can contribute to the improvement of the surface quality.