Circuit breaker

The invention relates to a circuit breaker which comprises an arc extinguish chamber barrel fixedly provided with an arc extinguish chamber and an operating mechanism arranged on one side of the arc extinguish chamber barrel, and a supporting structure supported on a movable support is arranged in the arc extinguish chamber barrel. The supporting structure comprises two electric conductors, the upper ends of the two electric conductors are connected through a closing resistor, and the circuit breaker comprises a closing resistor containing cavity used for covering the closing resistor. The circuit breaker further comprises a closing resistor static contact and a closing resistor moving contact, the closing resistor static contact comprises static contact split bodies arranged on the two electric conductors respectively, and the closing resistor moving contact is used for stretching into and being clamped between the two static contact split bodies so as to short-circuit the closing resistor. According to the