Anal fistula is a common disease in anorectology, which is an abnormal tube formed in the anal canal or rectum that is connected to the skin around the anus for pathological reasons. In Chinese medicine, it is also called hemorrhoidal leakage or anal leakage. The word “leakage” describes the symptom of pus overflowing from this disease. Modern medicine considers anal fistula and perianal abscess as two pathological stages of perianal interstitial purulent infection, respectively, perianal abscess in the acute stage and anal fistula in the chronic stage. The main manifestations are recurrent pus flow, pain, anal itching with poor defecation or systemic symptoms. Its incidence is second only to hemorrhoids, and the total number of incidences differs significantly at home and abroad, accounting for about 8-25%. In China, it accounts for about 1.67%-3.6%. The peak age of incidence is about 20-40 years old, and it is not uncommon for infants and children to develop the disease. Patients can feel a small nodule or a small package around the anus, or even a “pipe” leading to the anus. The nodule is the external mouth of the fistula, which can repeatedly bleed pus and overflow and contaminate the underwear, and can sometimes be closed with topical medication or without treatment, but almost most fistulas will recur without treatment of the primary infection and even form new sinus tracts based on the original fistula. Therefore, once a fistula is diagnosed, it should be treated surgically in a timely manner. In general, simple and low-grade fistulas are easy to treat, with relatively few complications and sequelae, while complex fistulas are more difficult to treat, and the goal of surgical treatment is both to cure the fistula and to preserve the function of the anus. The current surgical method to cure anal fistula is generally to remove the fistula more thoroughly so that the drainage is unobstructed, which is bound to damage the sphincter and anal tissues and affect the anal function, and if the lesion is not completely removed it is prone to recurrence.