Ordinary colonoscopy is usually deepest to the ileocecal or ileocecal end, and in the case of small colonoscopy, capsule endoscopy, etc. can also examine the small intestine. There are more categories of colonoscopes, including fiberoptic colonoscopy, capsule endoscopy, single or double balloon small colonoscopy, and so on. Ordinary colonoscopy generally examines lesions of the colon and rectum, mostly using fiber optic electronic colonoscopy, which enters through the anus and accesses the ileocecum or the end of the ileum, and colonoscopic observation of colorectal lesions is mainly carried out at the time of regression. In the case of single- or double-balloon small enteroscopes, the upper portion of the small bowel is accessed through the mouth and requires a second maneuver to enter through the anus and pass through the ileocecal flap to reach the lower portion of the small bowel, in order to complete the entire small bowel examination. In the case of capsule endoscopy, it is swallowed through the mouth, passed through the stomach, small intestine, colorectum, and discharged through the anus. Generally according to different conditions and patient needs will choose different colonoscopy mode, patients are recommended to weigh the pros and cons and then choose reasonably.