Electromagnetic repulsion mechanism is an important part of large capacity generator circuit breaker. The peak repulsive force of the electromagnetic repulsion mechanism is large and the action speed is fast. It takes a long time to carry out tens of thousands of mechanical life tests, which not only wastes manpower and material resources, but also affects the research and development cycle of repulsion mechanism. An automatic test device for mechanical life of high-speed repulsion switch is developed in this paper. Firstly, through the design of hardware and software, the functions of driving, parameter measurement, fault monitoring and automatic protection are realized, which greatly improves the efficiency of mechanical life test. After that, a prototype of mechanical life test system was built, and 7700 mechanical life tests were completed in 20 days. During the test, the excitation current waveform, main fracture signal, opening and closing time and other data are recorded. Finally, the repeated action characteristics are analyzed. The variation trend of the main mechanical life parameters of the high-speed repulsion switch is analyzed. Possible reasons are given. It provides a basis for further research on mechanical life.