Abstract: Beryllium copper ball socket structure has an important application in the inertial navigation system, and its machining accuracy directly affects the performance of the equipment, but the discharge particles generated during the electrical discharge machining (EDM) process will affect the accuracy of the ball socket structure. The timely expulsion of discharge particles poses a significant challenge in the EDM of ball socket structure. In this study, based on COMSOL software, the flow field simulation model of EDM ball socket structure was established, and the transport mechanism of dielectric flow and discharge particles were analyzed under different ultrasonic vibration parameters. It is found that without ultrasonic vibration, the machining gap is prone to eddy currents, which leads to uneven dielectric velocity and the phenomenon of accumulation of discharge particles. Ultrasonic vibration significantly enhanced the flow of the dielectric and promoted the expulsion of the discharge particles. Under the ultrasonic vibration condition, the proportion of remaining discharge particles in the machining gap decreased significantly from 45.76% without ultrasonic vibration to 4.93%. In addition, the ultrasonic vibration frequency and amplitude have obvious effects on discharge particle expulsion, and higher vibration frequency and moderate vibration amplitude help to improve the machining environment and improve the machining accuracy. The simulation results provide theoretical support for optimization of process parameters, which helps to improve the machining efficiency and precision for beryllium copper alloy ball socket structure.