The day before the colonoscopy can eat, but need to pay attention to the colonoscopy can not eat within 12 hours before the examination. The day before the colonoscopy can eat, but need to pay attention to food selection, should eat some easy to digest and absorb food, try to avoid a large amount of fiber-rich vegetables and fruits, this kind of food is more difficult to digest and easy to produce a larger fecal sludge, may affect the purging of intestines, resulting in poor intestinal preparation, which affects the results of the colonoscopy. Patients should have a light diet and avoid spicy and stimulating foods before having a colonoscopy so as not to irritate the intestinal mucosa. Patients with severe cardiopulmonary insufficiency, abdominal aortic aneurysm, abdominal adhesions leading to narrowing of the intestinal lumen, severe ulcerative colitis and during menstruation should not undergo colonoscopy, and should inform the doctor in advance. Patients who need to do colonoscopy should go to the hospital in time and make specific preparations before doing colonoscopy under the guidance of the doctor.