Anal bleeding during defecation can be divided into four cases. Specifically as follows: first, hemorrhoids as one of the common perianal diseases, clinical manifestations of anal blood dripping after defecation or defecation with blood on the surface, not accompanied by severe pain in the anus. Second, rectal malignant tumor, manifested as intermittent blood in stool or black stool, accompanied by systemic symptoms such as generalized emaciation. Third, anal fissure is common in patients with long-term constipation, manifested as blood dripping after defecation accompanied by severe anal pain, and the pain can be aggravated during defecation. Fourth, benign rectal tumors, such as rectal adenoma or rectal polyps. When the local capillary breakage can appear blood in the stool, the bleeding can be reduced and can stop by itself. When there is anal bleeding in defecation, it should be timely to regular medical institutions, fiberoproctoscopy, clear bleeding site and etiology, early detection, early treatment, to avoid causing serious clinical complications.