The invention provides a novel small-sized circuit breaker automatic switch-on and switch-off subminiature control mechanism and a circuit breaker. The novel small-sized circuit breaker automatic switch-on and switch-off subminiature control mechanism comprises a shell, a driving motor, a speed reduction gear group, a dual-layer special-shaped speed reduction switch-off incomplete gear, an air-switch release connecting rod, a linkage shaft driven switch-on incomplete gear and a spanner linkage shaft; the driving motor drives the speed reduction gear group to rotate to further drive the dual-layer special-shaped speed reduction switch-off incomplete gear and the linkage shaft driven switch-on incomplete gear to rotate so as to realize switching on; or a bump on the dual-layer special-shapedspeed reduction switch-off incomplete gear is in collision with one end of the air-switch release connecting rod to enable a release linkage shaft at the other end of the air-switch release connecting rod to drive a release linkage structure in the circuit breaker to be released so as to realize switching off. The novel small-sized circuit breaker automatic switch-on and switch-off subminiature control mechanism is compact in structure and small in size, and can realize automatic switching on and switching off control on the circuit breaker within a space of 9mm.