For the rationality of optimization of 126kV SF6 circuit breaker opening and closing, it calculates and analyzes the matching characteristics of circuit breaker and motor-driven actuator. And then, the corresponding relationship between the contact movement and the permanent magnet motor is obtained. The contact speed of circuit breaker is mainly determined by the rotation speed of permanent magnet motor. According to the velocity and travel characteristics of circuit breaker contact motion process for fault current breaking, the mathematical model of the electromagnetic and mechanical coupling field of permanent magnet drive motor is established and the system prototype is developed, which can locate the position accurately and adjust the speed, by using the finite element analysis method. The mechanical characteristic of the circuit breaker is tested, and the speed of opening and closing is respectively up to 3.7m/s and 2.1m/s, which fully satisfies the performance requirements of the circuit breaker. The operating mechanism has good controllability and stable operation characteristics, which makes it possible to realize the phase selection and phase separation of the high voltage circuit breaker.