The invention relates to an outdoor unit of an air conditioner, which comprises the following parts: a compressor, which supplies power to the refrigerant flow in the air conditioner; an outdoor heatexchanger, which performs heat exchange with the outside through refrigerant circulation; a fan, which accelerates the heat exchange between the outdoor heat exchanger and the outside through the airflow generated by self rotation; a fan motor, which is connected with the fan and supplies power to the fan; and an outdoor unit shell, which accommodates the parts and is provided with an outdoor suction inlet, wherein the heat exchanger of the outdoor unit is provided with a dehumidifier. When the air conditioner performs heating run under an outdoor low-temperature high-humidity condition, thecold air entering the outdoor unit shell passes through the dehumidifier first, the dehumidifier absorbs the moisture in the air so that the air becomes dry air, the dry air forms no dew on the surface of the heat exchanger when passing through the outdoor heat exchanger, and the outdoor heat exchanger cannot frost, so the times of performing defrosting operation by the air conditioner are reduced, the heating run is more consecutive, and the heating performance of the air conditioner is improved.