A circuit breaker, including a circuit breaker body, a handle, a bottom box, and a bearing plate. The circuit breaker body includes an upper cover, and a notch groove is formed on the upper cover. Two ends of the notch groove are positioned in the on/off position corresponding to the circuit breaker. The handle extends out of the notch groove. A circuit breaker actuating mechanism, a wire inlet end, and a wire outlet end are arranged on the bottom box. The circuit breaker actuating mechanism is triggered by the handle. The bearing plate is arranged between the upper cover and the bottom box and combined with an electrical operating mechanism. The handle is switched in the on/off state during the operation of the electrical operating mechanism under the control of an automatic closing control unit.