For more than 2000 years, the high incidence and recurrence of anal fistula has been a problem, with many patients suffering from recurrent attacks or recurrences after multiple surgeries, and the disease can last for years or even decades. Therefore, anal fistula, especially high anal fistula, is recognized as one of the most difficult diseases in the world of surgery today. The usual surgical interpretation of a fistula is that it is a granulation tube that joins two openings in the epithelial tissue. If one end of the tube is not open to the epithelial tissue, or if only one end is open, it is called a ‘sinus tract’. ‘Anal fistula’ is a very apt name for it. An anal fistula is the chronic stage of a perianal abscess, a specific disorder caused by an infection of the anal glands. There are three basic components of an anal fistula, namely the external opening, the fistula tract and the internal opening. The external orifice is the mouth where the perianal abscess breaks or is incised and is located in the skin around the anus, either close to the anus, mostly 2-3 cm from the anus, or far from the anus, either one or more. Some of the external openings are equal to the skin, some are depressed, and some are protruding. Some are also among the granulation tissue. The size and location of the external opening can infer the type of anal fistula. The main fistula is the fistula between the internal and the primary external orifice, either straight or curved, and can have a different anterior and posterior course around the anal sphincter. The internal orifice is the origin of the fistula lesion and the majority are located within the anal sinus. According to the theory of anal gland infection, the internal orifice of an anal fistula is never outside the dentate anal sinus.