In order to improve the breaking speed of miniature circuit breakers, RecurDyn Flux and Altair Flux were used to build an electromagnetic trip simulation model coupled with multi-body dynamics and electromagnetism to simulate the electromagnetic trip process in the event of short-circuit fault. It analyzes the dynamic characteristic curves during the contact separation process to explore the factors affecting the breaking speed, and the actual electromagnetic trip process was photographed by high-speed camera to verify the simulation model. Based on the simulation model, the orthogonal experiment is designed for the three factors that affect the breaking speed, and the optimal combination of factors is obtained. The test results show that the design scheme can increase the breaking speed of mini circuit breaker by 24.17% compared with the original prototype.