The reason for this is that there are many reasons: 1. internal hemorrhoids are bleeding, internal hemorrhoids are varicose veins and are usually located above the dentate line. The symptoms of internal hemorrhoids are usually painless bleeding. 2, rectal polyps and rectal adenomas, long-term fecal stimulation, easy to make the polyp surface mucosa rupture, resulting in stool blood, the blood is generally bright but does not cause pain. 3, if the rectal malignant tumor, invasion of the mucosa and submucosa blood vessels resulting in blood in the stool, the blood is bright red and does not cause pain. Therefore, there are many reasons for the bright red blood in the stool without pain, which should be combined with medical history, physical examination and, if necessary, anoscopy or colonoscopy to clarify the cause of blood in the stool.