Most acute anal fissures are caused by dry stool or dry head, which breaks the anal canal during defecation and causes painful bleeding, and the fissures are mostly in the middle of the back and front of the anus; a few are caused by infection and inflammation of the mucous membrane of the anal canal, which causes rupture of the mucous membrane of the anal canal during defecation, and the location of the fissures is variable and can be multiple, related to dry stool or unrelated. Treatment is generally based on preventing dry stools, preventing friction and promoting mucosal repair, and anti-inflammatory treatment for anal fissures caused by inflammation. Chronic prolonged anal fissure, generally known as old anal fissure. Repeated dry stool is also the main triggering factor, but only two-thirds of patients with dry stool will form anal fissures, and the other one-third, although dry stool is not easy to discharge, will never cause anal fissures; another important factor is mental tension (anxiety and depression), the lower third of the internal sphincter of the anal canal cannot be fully relaxed during defecation, or even stiffened and fibrotic, and less dry stool will cause anal canal Mucous membrane rupture, causing painful bleeding, mostly in the front and back of the median repeatedly, in a cyclical manner. It can cause sentinel hemorrhoids, anal papillary hypertrophy and subcutaneous fistulae, which are more frequent in mature and fertile women and are related to physiological and psychological contradictory factors of the intestinal tract. Surgical treatment is usually required to cure it. In addition to excision of the anal fissure tissue, incision and release of the lower end of the anal canal (about one-half) of the internal sphincter and the subcutaneous ring of the external sphincter are required. Not only does the anal fissure not recur, but it also facilitates the free flow of stool. This indicates that anal fissures are due to the overdevelopment and function of the internal anal sphincter.