The invention provides a remaining hydraulic spring mechanism used for an operating mechanism of a high-voltage circuit breaker. A hydraulic actuator adopts two hydraulic cylinders connected with in series, thus increasing the remaining of the hydraulic actuator while reducing the changes of other machines and hydraulic elements to the utmost extent, so that not only the reliability of the hydraulic actuator is improved, but also the piston action area is increased, thus expanding the scope of opening and closing speed of a breaker under normal running conditions.