Abstract: The permanent magnet actuator combines the electromagnetic mechanism with permanent magnets. With permanent magnet holding and electronic control, it achieves favorable matching of operating characteristics with vacuum circuit breakers. Benefiting from fewer moving parts and simplified intermediate conversion and connecting mechanisms, the dispersion and uncontrollability of operating time are greatly reduced. It realizes high mechanical reliability and maintenance-free operation as well as intelligent operation performance, and thus has been widely applied in the medium-voltage field. This paper focuses on the key design issues in the development of permanent magnet actuators and carries out calculations and research on its mechanical characteristics. The results can provide guidance for product design and optimization, reduce the time and cost of prototype verification, and improve the efficiency of product optimization.