Miniature circuit breaker

The utility model relates to a miniature circuit breaker, which comprises a base, a cover body arranged on the base, an operating mechanism, an electromagnetic release, a moving contact, a static contact, an arc extinguish chamber, a run-on plate, a first wiring terminal and a second wiring terminal, and is characterized in that the arc extinguish chamber comprises a flash barrier and a plurality of arc extinguishing grid sheets horizontally arranged in the flash barrier; one side of the flash barrier, which is far away from the static contact, is respectively provided with a plurality of air outlet holes which are distributed in a mutually staggered manner, an arc extinguishing channel is formed between the run-on plate and the static contact, the arc extinguishing channel is communicated between the moving contact and the arc extinguishing chamber, one end of the run-on plate is provided with an arc extinguishing part which is inserted below the arc extinguishing chamber, and the other end of the run-on pla