An anal fistula is a chronic infectious “channel” between the anal canal (or lower rectum) and the perianal skin, also known as “anorectal fistula”, which is called hemorrhoid leakage in traditional Chinese medicine and is a common anal disease. A fistula is a granulomatous tube that connects the anal canal or rectum to the perianal skin, mainly invading the anal canal and rarely involving the rectum, so it is often called an anal fistula. The entire fistula wall consists of thickened fibrous tissue with a layer of granulation tissue that does not heal over time. Anal fistula is an extremely common and difficult surgical disease, especially high complexity fistula is recognized as one of the most difficult diseases in the world of surgery today, with a recurrence rate of about 10% after surgery. According to recent statistics, the incidence of anal fistula accounts for about 3% of the total incidence of anorectal diseases in China. It can occur in both men and women, but is generally more common in young adults and more common in men than women. Patients with fistulas often have a history of self-rupture or incision and drainage of perianal abscesses, after which the wounds remain open for a long time. The clinical manifestation is a small amount of purulent, bloody, or mucus discharge from the external orifice of the fistula, which makes the anus moist and itchy due to the stimulation of the discharge, sometimes forming eczema. The skin grows quickly and often closes, resulting in the accumulation of pus in the fistula, which can cause local inflammatory manifestations such as redness, swelling, heat and pain, and even systemic infection symptoms such as fever and malaise, which are relieved when the abscess is punctured or reopened and drained. Due to the recurrence of symptoms, multiple external/internal openings can be formed, which can rarely be cured on their own, and perianal cancer can occur in patients who are not cured for a long time.