If the colonoscopy is to be performed in the morning of the following day, oral laxatives should be taken the night before to prepare the bowel; if the colonoscopy is to be performed in the afternoon, the bowel can be prepared in the morning of the same day. Patients need to take laxatives and drink a lot of water before the colonoscopy, in order to clean and empty the feces in the intestines, so as to avoid the intestinal debris affecting the microscopic field of view. If the colonoscopy is to be performed in the morning of the following day, oral laxatives should be taken the night before for bowel preparation; if the colonoscopy is to be performed in the afternoon, bowel preparation can be performed in the morning of the same day. Three days before the colonoscopy, you need to pay attention to adjust the diet, try to avoid eating more residual food, so as not to affect the colonoscopy. If patients experience discomfort during or after the colonoscopy, they should consult a doctor in time to avoid adverse consequences.