A smart air conditioner for reduction in fine dust and harmful gas includes: an eternal chamber including a first side coupled to communicate with an interior and a second side communicating with an exterior; an internal chamber disposed to pass through an inside of the external chamber and including a first side coupled to communicate with an interior and a second side communicating with an exterior; an external chamber damper installed in the external chamber and controlling air flow; and an internal chamber damper installed in the internal chamber and controlling air flow.