Three-year-old boys with fissures on the upper side of the anus may be related to anal trauma, or may be caused by anal fissures or perianal eczema. 1. Trauma: usually caused by contusion, firearm injury or sharp instrument injury, etc., due to anal trauma, it may lead to three-year-old boys with fissures on the upper side of the anus, which may also be accompanied by anal bleeding, pain, difficulty in defecation and other symptoms. 2. Anal fissure: usually caused by long-term constipation, frequent diarrhea, inflammatory diseases of the anal tract and other reasons, can lead to local skin damage in the anus, which may lead to fissures in the anus, may also be accompanied by perianal itching, pain, bleeding and other manifestations. 3. Perianal eczema: mainly due to a long time to stay in the hot and humid environment caused by perianal eczema, may lead to localized skin damage in the affected area, which may cause fissures on the anus, may also be accompanied by perianal itching, pain and other symptoms. More than three-year-old boy with fissures on the upper side of the anus, may also be caused by other reasons, it is recommended to consult a doctor as soon as possible, after a clear diagnosis of the cause, by the doctor’s guidance for treatment and conditioning.