An anal fistula is a granulomatous canal around the anus, consisting of an internal, fistula and external opening, and is most commonly seen in young adults. According to the location of the fistula, it can be divided into high anal fistula and low anal fistula. According to the relationship between the fistula and the sphincter, it can be divided into inter-anal sphincter, trans-anal sphincter, supra-anal sphincter and extra-anal sphincter. The clinical manifestations are repeated purulent and bloody discharge from the anal orifice, and dampness and itching of the anal area. It is not self-healing. The treatment methods are: 1. blockage method; 2. surgery: fistulotomy, which can be performed under sacral anesthesia or local anesthesia; hanging wire therapy: its biggest advantage is that it does not cause anal incontinence, simple operation, less bleeding, and no drug change; fistulotomy: it is suitable for low simple anal fistula.