Abstract: The application provides an air handling unit, comprising: an air flow path having an outdoor air inlet on the upstream side of the air flow path and an indoor air outlet on the downstream side of the air flow path; an high efficient filtering portion disposed in the air flow path and covering at least a part of a cross section of the air flow path; a bypassing portion disposed in the air flow path in parallel with the high efficient filtering portion and covering the other part of the cross section of the air flow path; a data sensing portion disposed upstream of the bypassing portion and used to sense air quality parameters of air flowing through the data sensing portion; and a controller controlling an open/close state of the bypassing portion based on the air quality parameter sensed by the data sensing portion.