The invention provides a support frame, a base assembly and an air purifier. The support frame comprises an air flue inner frame, an air flue outer frame and supporting ribs; the air flue outer frame is arranged on the outer side of the air flue inner frame in a sleeving manner; and the supporting ribs are arranged between the air flue inner frame and the air flue outer frame, and a space between the air flue inner frame and the air flue outer frame is hollowed to form a side air inlet. The space between the air flue inner frame and the air flue outer frame is hollowed to form the side air inlet, compared with a supporting frame with a single function in the prior art, the supporting frame serves as a part of an air inlet air flue, the function of the supporting frame is additionally arranged, and the air inlet amount can be effectively improved.