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 skin around the anus and can be one or more. The symptoms of anal fistula 1, poor anal venous reflux, frequent local bruising, and poor tissue nutrition, which affects healing. 2, the fistula tract is bent, or has sinuses, branches, poor drainage, retention of pus, repeated infections, resulting in fistula tracts that do not heal easily. 3, there is a certain pressure in the rectum, will rectal infection material such as feces, gas, can often constantly from the inner mouth into the fistula, stimulate the cavity wall, secondary to infection from the outer mouth, is also the cause of fistula. 4, after the perianorectal abscess breaks, the pus is discharged, the pus cavity gradually shrinks, the external rupture and incision also shrinks, and the cavity wall forms a hard duct wall with proliferation of connective tissue, and thus cannot be closed naturally. 5, fistula passage between the anal sphincter, because the sphincter often constantly contract and diastolic, compression of the fistula, affecting the exclusion of pus, easy to store pus infection and difficult to heal. 6, anorectal perineal abscess breaks or incision mostly outside the anus, pus flows from the external mouth, but the primary infection is mostly in the anal sinus. The anal sinus is then the portal of secondary infection, repeatedly infected and forming a fistula. 7, abscesses formed by infections such as Mycobacterium tuberculosis and Actinomyces, Clonorchiasis, etc. are difficult to heal by themselves and form special anal fistulas.