1.Blood in the stool or mucus stool has been ruled out anal disease, the cause of which is unknown; 2.Recurrent episodes of abdominal pain and diarrhea; 3.Barium enema or clinical high suspicion of colonic malignancy; 4.Barium enema found ileal lesions and can not be determined; 5.Colonic polyps or ulcerative colitis to clarify the scope of specific lesions; 6.Colonic polyps need to be removed by fiberoptic colonoscopy; 7.Intraoperative lesions of the large and small intestine 7.Large and small intestine lesions cannot be clearly located or multiple polyps in large and small intestine need to be removed by intraoperative fiberoptic colonoscopy; 8.Pseudocolonic obstruction needs to be removed by fiberoptic colonoscopy; 9.Intestinal overlap and intestinal torsion need to be clearly diagnosed and reset; 10.Colorectal cancer or colorectal polyps need to be reviewed after surgery and colorectal lesions need to be regularly followed up and observed.