The invention relates to a millet hull rethreshing cylinder, a rethreshing cleaning device and a combine harvester. The combine harvester comprises a vehicle body, the rethreshing cleaning device is mounted on the vehicle body and comprises the millet hull rethreshing cylinder, the millet hull rethreshing cylinder comprises an outer cylinder body, two ends of the outer cylinder body are provided with a feed port and a discharge port respectively, an inner cylinder body is coaxially arranged in the outer cylinder body, the outer cylinder body and the inner cylinder body are rotationally fitted,at east one of the inner surface of the outer cylinder body and the outer surface of the inner cylinder body is provided with a screw vane for material conveying, a conveying passage is formed between the inner and outer cylinder bodies, and compress rollers cooperating with the inner surface of the outer cylinder body and/or the outer surface of the inner cylinder body to roll-thresh millet hulls passed through are arranged between the inner cylinder body and the outer cylinder body. When the combine harvester is used to harvest millets, the compress rollers can roll the millet to effectively thresh the millet hulls, the millet hulls can be effectively removed, and millet hull threshing rate and harvesting efficiency of the combine harvester are greatly increased.