Before the colonoscopy should be careful not to eat high fiber content of fruits and vegetables, stop using anticoagulant drugs or blood-activating drugs, etc., 3 to 6 hours before the examination needs to be fasting and water. Laxatives such as mannitol need to be taken before the examination. Before the colonoscopy in order to ensure the cleanliness of the intestines during the colonoscopy, it is recommended to try not to eat fruits and vegetables with high fiber content 3 days before the examination, because high-fiber foods take a long time to digest after consumption, and can not be easily discharged by the intestines, which may affect the colonoscopy. One week before the examination, stop using anticoagulant drugs or blood-activating drugs to prevent gastrointestinal bleeding, and abstain from food and water for 3 to 6 hours before the colonoscopy. Avoid food digestion in the stomach will have all kinds of residues stay in the intestines, affecting the doctor’s observation of the intestines. Oral laxatives such as mannitol before colonoscopy, 4~8 hours before the operation, 10% solution 1000ml in 30 minutes orally, to achieve the effect of intestinal cleansing. In the first three days after colonoscopy, try to eat semi-liquid porridge or easily digestible food, do not eat cold, spicy and stimulating food. Normally, pay more attention to the maintenance of the stomach and intestines, eat more fresh fruits and vegetables.