Gastroenteroscopy refers to both colonoscopy and gastroscopy. Before the colonoscopy, you need to pay attention to diet, clean up the intestinal contents, avoid menstruation and pregnancy, etc. Before gastroscopy, it is necessary to pay attention to fasting, water fasting, avoiding menstruation and pregnancy, and so on. 1. Preoperative preparation and precautions for colonoscopy: (1) Three days before the colonoscopy examination, you need to eat semi-liquid or less residual food, such as: thin rice, noodles and so on. It is generally required to fast for more than eight hours before the examination. (2) Three days before the examination need to stop taking iron medicines. (3) Clean up the intestinal contents, currently common laxatives plus enema, catheterization method. The main purpose is to empty the intestinal contents, until the discharged stool is clear water or light yellow, no fecal sludge is the best intestinal cleansing effect. (4) Patients need to strictly follow the doctor’s instructions to carry out other related projects, but also need to be fully prepared for the ideological, remove concerns and fears. (5) When performing colonoscopy, it is necessary to avoid menstruation and pregnancy. 2. Gastroscopy preoperative preparation and precautions: (1) Fasting is required after 12:00 p.m. on the night before the examination, and fasting and water restriction are required in the morning of the examination. (2) You need to take antifoaming agent and local anesthetic before the gastroscopy and remove the movable dentures. Specific precautions before the gastroenteroscopy can vary depending on the specific condition and are subject to the requirements of the interviewing doctor.