Compared with traditional EDM, ultrasonic vibration assisted EDM ((UEDM)) shows better performance in machining efficiency and surface quality. But the material removal process of UEDM is complex, and there are many influencing factors, so it is difficult to describe the material removal process accurately. In this study, based on the voltage variation during UEDM processing and combined with the heat transfer theory, the material removal model of TC4 titanium alloy under the condition of single pulse vertical ultrasonic vibration UEDM was established, and the material removal process of UEDM under different amplitudes was analyzed. The machining efficiency and surface quality of UEDM with different ultrasonic energy under the condition of vertical ultrasonic vibration are obtained verified by UEDM experiments. The best ultrasonic energy under different current can be obtained by adjusting the current and ultrasonic vibration energy, which can improve the efficiency of UEDM.