According to clinical experience, it is recommended that: First, for the general population without a family history of colorectal tumors, if economic conditions allow, the first colonoscopy should be done at the age of 50, and if there is no abnormality, then every 3-5 years thereafter; if adenomatous polyps are found, they should be removed as early as possible, and a colonoscopy review should be performed once a year after surgery. If conditions do not allow, stool occult blood test can be performed, and those who are positive will undergo colonoscopy again. Secondly, if a parent or sibling has bowel cancer in his or her immediate family, he or she should undergo colonoscopy at the right time; Thirdly, if a non-immediate family member under the age of 50 finds bowel cancer, he or she should go to the hospital and undergo colonoscopy in time; Fourthly, if the following symptoms persist for two weeks or more, he or she should go to the hospital for examination (2) Mucus and blood stools: the stools are often filled with bright red or dark red blood and mucus; (3) Urgency and heaviness: the feeling that the stools are not finished, but the stools cannot be defecated; (4) Persistent abdominal pain; the pain is mostly in the lower and middle abdomen, with varying degrees of severity, mostly vague pain or distension; (5) Anemia is often accompanied by fatigue and unexplained sudden weight loss.