Bleeding from a tear in the anal opening of the stool is commonly associated with anal fissure. Anal fissure is a small ulcer formed parallel to the longitudinal axis of the anal canal after the skin layer of the anal canal is cracked under the dentate line, mostly seen in young and middle-aged people, often accompanied by severe pain in the perianal area. The cause of anal fissure is not yet clear, long-term constipation, fecal dryness caused by mechanical trauma is mostly its direct cause, in addition, diarrhea is also an important reason for the formation of anal fissure. Typical clinical manifestations of anal fissure patients can be seen in anal fissure, anal papilla hypertrophy, anterior sentinel hemorrhoids (fissure of the lower end of the skin in the form of a pouch hanging downward protruding out of the anus). It can be treated by warm water sitz bath, but it is easy to recur and can be treated surgically if necessary. Found anal fissure, should immediately to the hospital anorectal department consultation, clear diagnosis, standardized treatment, follow the doctor’s instructions.