Circuit breaker

The utility model discloses a circuit breaker, which comprises a base and a cover body arranged above the base, the base is divided into at least two pole chambers by a spacing rib; a lower wiring channel is arranged on a spacing rib of the base, an upper wiring channel is arranged on the cover body, and the upper wiring channel and the lower wiring channel are communicated and penetrate through the base and the cover body. A first circuit board assembly is arranged on the cover body, and a transmission conductor of the first circuit board assembly extends into the back surface of the base through the upper wiring channel and the lower wiring channel; a first annular structure is arranged on the periphery of an upper opening of the lower wiring channel, and a second annular structure is arranged on the periphery of a lower opening of the upper wiring channel. One of the first annular structure and the second annular structure is of a convex structure, the other one of the first annular structure and the secon