The invention discloses a dust collection device and method of an aluminium oxide roasting furnace. The dust collection device comprises a cloth bag dust collector, a first distributor, a second distributor and a dust returning pipeline. One end of the first distributor is connected with a flue gas outlet of the roasting furnace, and the other end of the first distributor is connected with the cloth bag dust collector through a pipeline. The first distributor is a box body, an airflow distribution plate is mounted in the box body, and the airflow distribution plate constitutes a horn-shaped channel with a narrow inlet and a wide outlet. One end of the second distributor is connected with the cloth bag dust collector through a pipeline, the other end of the second distributor is connected with a draught fan, and the second distributor is a box body. One end of the dust returning pipeline is connected with the cloth bag dust collector, and the other end of the dust returning pipeline is connected with the roasting furnace. According to the dust collecting device and method of the aluminium oxide roasting furnace, in the flue gas purification process of the aluminium oxide roasting furnace, efficient and stable operation, safety and energy saving can be achieved, the exhaust gas emission concentration can meet the standard demand of environmental emission in China, and the cloth bag dust collection device and method of the aluminium oxide roasting furnace can be used for replacing an existing electric dust collection and purification technology of the roasting furnace.