Circuit breaker

A circuit breaker comprises a shell, a contact mechanism and an arc extinguish chamber, the contact mechanism and the arc extinguish chamber are arranged in the shell, the arc extinguish chamber is used for extinguishing electric arcs generated when the contact mechanism is disconnected, and the circuit breaker is characterized in that a cavity is further formed in the shell and provided with an inlet connected with an air outlet of the arc extinguish chamber and an outlet communicated with the outside of the circuit breaker, and the inlet is communicated with the air outlet of the arc extinguish chamber. Arc gas discharged from the gas outlet of the arc extinguish chamber enters the cavity through the inlet, a guide device is arranged in the cavity, the path of the arc gas in the cavity is U-shaped under the guidance of the guide device, and the outlet is formed in the bottom wall of the shell. The circuit breaker has the advantages that an arc gas discharge path is changed, and the gas outlet of the circuit