Abstract: A paper straw capable of a ninety-degree bend is compositely formed by spirally rolling a paper strip and trimming two ends of the rolled paper strip. One end of the straw is evenly configured with eight to twelve annular grooves by pressing. The paper strip is formed by combining a first paper layer, a second paper layer, and a third paper layer, so that the straw would not get soft during use. By configuring a plurality of annular grooves with a predetermined interval, the straw is capable of being fully bent by ninety degrees without significantly reducing the inner diameter of the straw at the bent region. The paper straw can be fully degraded after use, so no plastic pollution will be caused, and puts less pressure on the environment. Therefore, the paper straw can effectively replace the plastic straw used in the market.