Titanium alloys are widely used in aerospace, automotive, and medical industries due to their excellent material properties such as high strength-to-weight ratio, excellent corrosion resistance, and good biocompatibility. In this study, a series of ultrasonic elliptical vibration cutting (UEVC) simulations were carried out based on the experimentally verified finite element model, and different cutting speed ratios k were formed by changing the parameters such as frequency and cutting speed, so as to explore the influence of UEVC separation characteristics under different k on the cutting force and surface morphology of Ti-6Al-4V during the cutting process. The results show that compared with CM, the average cutting force of UEVC is reduced by 66% and 5% at k = 0.2 and k = 1.4, respectively, and the average cutting force reduction effect of UEVC decreases with the increase of k. At k < 0.8, the reduction rate of UEVC cutting force is almost the same as that of the workpiece, and the complete separation of the tool from the workpiece is the main factor for the reduction of the average cutting force. At k > 0.8, the separation of the tool from the workpiece basically disappears, and the reduction effect of UEVC cutting force is reduced from 28–5%. The reduction in cutting forces is mainly due to the fact that the UEVC still has separation characteristics in the direction of the depth of cut. The surface quality of UEVC processing will deteriorate with the increase of k at k < 1, and the surface quality of UEVC processing will no longer be affected by k at k ≥ 1. Under the condition that k remains constant, the average surface roughness Ra increases with the increase of both f, regardless of whether it is by changing f or by changing the amplitude, and the increasing trend is almost the same. The main difference is that by changing f, the compressive stress of the cutting surface will decrease as f increases; By varying the amplitude, the compressive stress on the cutting surface increases as the amplitude increases.
