The utility model relates to a circuit breaker and spring operating mechanism thereof, the spring operating mechanism is including the flywheel wheel and the driven energy storage pinion of flywheel wheel meshing that are used for driving energy storage spring compression, the flywheel wheel is the monolithic structure that integrative process formed, flywheel takes turns to and is equipped with the recess that is used for the installation to prevent the energy storage bits in its non - tooth period number department of putting, prevented that the energy storage bits was through the pivot, spacing hub connection takes turns to at flywheel, but prevent an energy storage bits about shaft rotation constant angle degree, spacing axle is controlled the turned angle scope of preventing the energy storage bits, be equipped with the roof pressure in the recess prevent the reset spring of energy storage bits. The utility model provides a flywheel wheel adopts integrative process fashioned, and processing technology is ripe and simple, and the precision of tooth is also guaranteed easily, and is more smooth and easy with the meshing of energy storage pinion.