Most anal fistulas are formed when an anorectal abscess breaks down or is incised to drain the pus. The abscess gradually shrinks, but the intestinal contents continue to enter the abscess cavity, in the process of healing and shrinking, often forming a tortuous cavity, poor drainage is not easy to heal, and after a long time there are many scar tissue around the cavity, forming a chronic infectious pipeline. In Chinese medicine, this disease is called “hanging carbuncle”, “sitting horse carbuncle”, “dirty poison”, etc. It is mostly caused by the rupture of perianal abscesses around the rectum and the formation of granulomatous canals around the anus that do not heal over time. It mostly occurs in men aged 20 to 40. Anal fistulas generally consist of a primary internal opening, a fistula arm, and a secondary external opening. Most of the internal openings are located near the dentition line, mostly one, and the external openings are located on the perianal skin and can be one or more.