There is no definite conclusion on how long an anal fissure is considered an old anal fissure, but generally chronic anal fissures longer than 3 months become old anal fissures and require surgical treatment. Anal fissures are small ulcers formed after the skin layer of the anal canal under the dentate line is cracked, and are divided into acute and chronic fissures. It is mostly seen in young and middle-aged people. Patients with anal fissures may present with typical clinical manifestations such as pain, constipation and bleeding. In the case of acute anal fissures, the duration of the disease is usually short, with neat fissure edges and no scar formation. In the case of chronic fissures, due to repeated injury and infection, the base is deep and uneven, hard and thickened by fibrosis, and old fissures will form in about 3 months. In addition, patients with anal fissures should also pay attention to eating more fresh vegetables, fruits and coarse fiber food in daily life, drink more water to promote gastrointestinal peristalsis and prevent constipation to reduce the possibility of developing into old anal fissures.