The kinematics of a single abrasive particle in three-dimensional Ultrasonic Vibration Assisted Grinding （UAG） was analyzed. The ultrasonic vibration assisted grinding experiment of zirconia ceramics was carried out with the self-built three-dimensional UAG system. By comparing the normal grinding force， surface roughness， and surface morphology of zirconia ceramics under different ultrasonic-assisted conditions， the influence of different processing parameters on the three-dimensional UAG process and the influence of three-dimensional ultrasound on the grinding process were studied. The experimental results show that the normal grinding force of zirconia ceramics decreases with the increase of ultrasonic assisted machining dimension. Three-dimensional UAG machining can effectively reduce the grinding load， and the influence of machining parameters on the reduction of normal grinding force is the smallest. The reduction of normal grinding force decreases with the increase of feed speed and cutting depth and increases with the increase of spindle speed. The surface roughness of zirconia ceramic workpieces decreases with the increase of ultrasonic assisted processing dimension， and the surface morphology gradually shows more plastic scratches. The influence of processing parameters on the surface roughness of three-dimensional UAG grinding is also the smallest. It can be seen that the increase of the cutting trajectory length of the single abrasive particle in the three-dimensional UAG machining is beneficial to the decrease of the cutting thickness， thus reducing the grinding force and improving the surface quality.