The invention discloses an air heating device of a flourmill. The air heating device comprises a boiler, a diversion air box, a condensate water storage tank, a tap water storage tank and a liquid level relay. The boiler is connected with the diversion air box through a pipeline. The diversion air box is connected with the condensate water storage tank through a pipeline. The condensate water storage tank is connected with the boiler through a pipeline. The boiler is connected with the tap water storage tank through a pipeline. The liquid level relay is arranged inside the tap water storage tank. The air heating device of the flourmill has the advantages of being high in heating capacity and thermal efficiency, remarkable in energy saving effect and the like.