The dietary preparation before colonoscopy is mainly seen in the following points: 1. 3 days before the colonoscopy should start a slag-free diet, mainly soft food, semi-liquid food, such as noodles, rice, steamed bread, egg custard and porridge food. Because of the low residue content of these foods, it is not easy to accumulate in the intestine to affect the intestinal preparation before colonoscopy. Avoid eating high fiber foods, such as celery, greens, etc., as these foods form more feces after digestion, which can affect the late intestinal preparation. 2. 1 day before the colonoscopy, you can eat semi-liquid food in the morning, such as noodles, rice porridge and egg custard, etc. Lunch is mainly liquid food, such as rice oil, lotus root powder, soy milk and milk, etc. At dinner time, fasting is started. You can drink water appropriately and take oral medication for intestinal preparation according to the doctor’s arrangement to promote the excretion of intestinal contents.