The invention discloses a titanium alloy ultraprecision machining method based on an ultrasonic elliptical vibration cutting technology. The titanium alloy ultraprecision machining method comprises the following steps: I, adjusting and controlling the temperature, the humidity and the air cleanliness of an ultraprecision machining laboratory; II, performing a pilot run on a machine tool; III, debugging an ultrasonic elliptical vibration cutting system; IV, mounting an ultrasonic elliptical vibration cutting device; V, mounting a titanium alloy material; VI, performing rough cutting; VII, performing semi-finished cutting; VIII, performing finish cutting; IX, performing ultrasonic elliptical vibration assisted cutting; and X, stopping an ultraprecision machine tool and the ultrasonic elliptical vibration cutting system, taking down a titanium alloy workpiece, cleaning the titanium alloy workpiece with absolute ethyl alcohol, performing drying, and then storing the titanium alloy workpiece to obtain an ultraprecision titanium alloy surface machined by the ultrasonic elliptical vibration cutting technology. The ultrasonic elliptical vibration cutting technology is adopted to realize ultraprecision machining of titanium alloy. The titanium alloy ultraprecision machining method has the advantages that abrasion of a cutter can be effectively inhibited, pits and microcracks on a machined surface are inhibited, the surface integrity of the workpiece is improved, and the damage degree of a subsurface of the workpiece can be effectively reduced.