The characteristics and symptoms of anal fistula can develop at any age, including infants and young children, and is more common in young adults and in males than females, but some infants and young children with anal fistula will heal on their own as their bodies and intestinal immune function improve. In adults, anal fistula is an infectious disease in which bacteria invade from a weak or broken mucosa in the anus (usually the anal fossa) and spread to the surrounding area and outside the anus to form an anal fistula. The clinical manifestations of anal fistula are repeated local pus flow, long-standing failure to close the mouth, painful accumulation of pus when the external mouth is closed, or fever. On examination, the fistula can be palpated or probed with a strip leading into the anus. If the fistula is not treated in time, it will easily complicate the fistula and affect the quality of life in addition to the pain associated with the disease, such as frequent pus overflow and contamination of clothing; local skin is often stimulated, which can lead to eczema and itching, affecting work, study and life. The majority of anal fistulas start out as simple anal fistulas, and as the disease recurs, they either become complex fistulas with multiple fistulas or develop deeper into high anal fistulas. The more complex the fistula, the more perianal tissues and anal sphincter are invaded, which makes surgery more difficult and traumatic, and can even affect the patient’s anal function and, in severe cases, fecal incontinence. In addition, recurrent anal fistulas have a certain possibility of becoming cancerous. Therefore, timely surgical treatment is important.