Anal fissures are small ulcers that form after the skin layer of the anal canal is fractured below the dentate line. Most of them are found in young and middle-aged people and are located in the posterior midline of the anal canal, but also in the anterior midline. If it is on the lateral side, care should be taken to exclude the possibility of inflammatory bowel disease or tumor. Prolonged constipation and dry stool are the direct causes of anal fissures. It has the typical manifestations of pain, constipation, and bleeding. Acute or incipient anal fissures can be treated with sitz baths and laxative methods, while chronic fissures can be treated with sitz baths, laxative and anal dilation methods. The principle of non-surgical treatment is to release the spasm of the sphincter, relieve pain, assist in defecation, interrupt the vicious cycle and promote local healing. Surgical treatment includes excision of anal fissure and internal sphincterotomy.