Tungsten heavy alloy has been widely used in the nuclear industry, military, and other fields due to its excellent material properties. In this paper, the wear of single crystal diamond tool and its influence on surface roughness were studied by ultrasonic elliptical vibration cutting experiment of tungsten heavy alloy and compared with conventional cutting. The experimental results show that under ultrasonic elliptical vibration cutting, the flank wear of a single crystal diamond cutter is reduced by 74.5%, and the retreat of the cutting edge is reduced by 70.6%. After the cutting experiment, the elements on the cutting surface, chip surface, and diamond tool adhesion were detected and analyzed by Raman spectroscopy and X-ray photoelectron spectroscopy. The results show that compared with conventional cutting, ultrasonic elliptical vibration cutting can effectively inhibit the graphitization of single-crystal diamond tools and avoid chemical wear. This is an essential reason why single-crystal diamond tools can be used for tungsten heavy alloy processing under ultrasonic elliptical vibration cutting.