This paper analyzes the operation mode and structure combination of the fast operating mechanism, and designs a fast operating mechanism composed of a mono-stable permanent magnet mechanism and a double-coil repulsion by using the high reliability and strong controllability of the permanent magnetic mechanism and the characteristics of the electromagnetic repulsion mechanism, such as fast action speed and short touch time. The finite element model of the fast operating mechanism is established by using ANSYS Maxwell, and the static and dynamic simulation calculations are carried out, so that the designed fast operating mechanism can meet the characteristic requirements of the fast vacuum circuit breaker. In view of the long closing bounce of the fast vacuum circuit breaker, an in-depth study is made, and the optimal way to intervene in the hydraulic buffer at the position 14 mm before the closing point of the circuit breaker is given. The closing bounce is reduced to 0 ms. The opening time of the 40.5 kV fast vacuum circuit breaker break-brake time is 3.6 ms, the closing time is 14.6 ms, the closing bounce is 0 ms, the short-circuit breaking current is 31.5 kA, and the short-circuit closing 80 kA, which can meet the technical requirements. The prototype has passed the capacity test, 10 000 times of mechanical life, temperature rise, insulation and other tests at the Power Industry Quality Inspection and Test Center for Electric Power Equipment and Instrument.