Al2O3 is widely applied in various industrial fields owing to its excellent physical, chemical and mechanical properties. However, its high hardness, pronounced brittleness, strong wear resistance and low thermal conductivity make it extremely difficult to machine. Rotary ultrasonic machining (RUM) has emerged as an effective technique for machining hard and brittle materials because of its ability to significantly reduce cutting force, improve surface finish and extend tool life. Based on an independently developed double-bending vibration rotary ultrasonic elliptical machining system, experiments were conducted on conventional grinding as well as one-dimensional and two-dimensional ultrasonic vibration-assisted grinding of Al2O3. The effects of process parameters on machining performance under different machining modes were systematically investigated, and the variation trends of maximum cutting force and surface roughness were quantitatively analyzed. Compared with conventional machining, rotary ultrasonic machining significantly reduces both cutting force and surface roughness, while two-dimensional rotary ultrasonic elliptical machining exhibits superior machining performance over its one-dimensional counterpart. These results not only confirm the significant advantages of double-bending vibration rotary ultrasonic machining in processing Al2O3, but also provide an important experimental foundation and theoretical guidance for extending the application of this technology in precision machining.