In recent years, with the change of disease spectrum, the incidence of colorectal cancer is increasing and getting younger, according to authoritative institutions, colorectal cancer in Shanghai, regardless of male or female, is steadily ranked second. Colonoscopy is a diagnostic method used by doctors to examine the internal lesions of the colon and colon, and has an irreplaceable role in diagnosing intestinal occupational lesions, intestinal polyps, colonic ulcers, chronic colitis or clamping pathology and minimally invasive surgery under colonoscopy, and is still the easiest, safest and most effective method to detect intestinal tumors and precancerous lesions. Painless colonoscopy refers to the use of general anesthesia in a short period of time to help patients perform colonoscopy and treatment in a sleep state, which is safe and effective. The advantages are: high patient compliance, no interruptions during the examination due to intolerance; and the patient is in a relaxed state, so that the examiner has a clear view and the examination is comprehensive and thorough. Colonoscopy should be done for: 1, patients with enteritis, long-term medication, long-term treatment; 2, long-term diarrhea, abdominal pain, constipation treatment is ineffective; 3, more than 40 years old, stool habits change or body recently rapid weight loss; 4, mucus, pus and blood in the stool; 5, long-term itching in the anus or long-term perianal drop; 6, colon tumors, polyps after surgery or inflammatory bowel disease regular follow-up.