The most common cause of bleeding is hemorrhoids, the main feature of hemorrhoids bleeding is blood dripping from the stool or blood when wiping after the stool, the color of the blood is bright red, not accompanied by anal pain. 2, consider anal fissures, anal fissures are mostly caused by dry, hard, constipated stool, manifested as anal pain when stooling, accompanied by blood dripping or wiping. 3, consider anal skin fissures, mostly due to anal itching or anal eczema, long-term scratching, resulting in anal skin cracking, accompanied by itching pain. The most common cause of anal skin fissures is anal itching or anal eczema, long-term scratching, resulting in skin fissures around the anus, manifesting as blood when wiping after the stool, accompanied by anal itching and pain, etc. 4, to consider whether the bleeding is caused by other lesions in the rectum or colon, especially bleeding caused by rectal and colon tumors, which should be taken seriously and should be promptly examined by electronic colonoscopy. Only then can the diagnosis be clear.