Anal fistula is a disease that forms after the rupture of a perianal abscess, and can be divided into low and high anal fistula according to the clinical location of the fistula; and simple and complex anal fistula according to the complexity. The combination of these two types of fistulae can be divided into four categories: low simple fistula, low complex fistula, high simple fistula, and high complex fistula. The classification of anal fistula basically determines the way of surgery and anesthesia, regardless of the type of fistula, it should be treated surgically, not by medication or some other unregulated treatment, and it is the most complex disease in anorectology, and also the disease with the highest recurrence rate, a disease that can be malignant and easy to cause The most important problem of anal fistula surgery is that it is the most complex and recurrent disease. The two major problems of anal fistula surgery are: the first is the problem of postoperative recurrence, and the second is the problem of sphincter damage. The problem of sphincter injury is very complicated, and the degree of injury varies, causing different degrees of postoperative fecal incontinence. In many cases, the anal overflow is not stool or loose stool, but some intestinal fluid and rectal secretions overflow more, which occurs often with underwear contamination, causing dampness, itching, and perianal eczema at the anal opening, causing patient dissatisfaction and easily causing medical disputes. The fistula is not an ordinary disease and should attract the attention of every physician. After receiving the patient, we should take a detailed medical history, carefully examine the body, and if it feels complicated or high, we must have an MRI examination, which can find multiple internal openings, as well as multiple fistulas, and the greatest significance is that the alignment of the fistula and the anatomical relationship with the sphincter can be found, providing the basis for designing the surgical plan before surgery. The most important thing is to find out the shape of the fistula and the anatomy of the sphincter before surgery. It is important to decide whether or not to have an MRI examination. The surgical concept of anal fistula is the most important thing to decide whether or not to cause fecal incontinence after surgery, years of clinical experience, to protect the sphincter muscle should be like protecting their eyes to be able to, because the main structure to control the stool is the anorectal ring, as long as the anal anorectal ring is not broken, there will be no complete incontinence of the stool, this is true, but if the external sphincter and internal sphincter muscle damage is more, will still However, if there is more damage to the external and internal sphincters, incomplete fecal incontinence may still occur, especially in elderly patients, tumor patients, tuberculosis patients, and patients with chronic renal insufficiency, who are weak and have poor sphincter elasticity and are more likely to suffer from fecal incontinence after surgery. In the case of low anal fistula, the anorectal ring is not damaged, it is time to protect the internal and external sphincter, although the damage is minimal, it is also best to hang the skin band, but most doctors use no skin band, a one-time cut, hanging the skin band is a really effective way to protect the sphincter, does not increase the cost, and does not prolong the operation, it is recommended to hang the skin band. If the fistula crosses the rectal ring, the anus must be examined before surgery to check the height, elasticity and fibrosis of the rectal ring, and the ring must be probed during surgery.