The whole process of colonoscopy includes two parts: the preparation before the examination and the examination process. 1. Pre-examination preparation: avoid eating fiber-rich food 1 day before the examination; for those who are constipated, eat a semi-liquid diet with less residue for several days in advance, and then enter a liquid diet in the night before the examination; if necessary, take a laxative, and take a laxative 4 hours in advance on the same day, and drink 1,500 to 2,000 ml of water until the discharged material is clear and water-like. 2. Examination process: the patient first take the left lateral position, do rectal fingerprinting, the operator’s right hand holding the mirror, will be coated with lubricating oil enteroscope apex oblique inserted into the anus, the left hand holding the maneuvering part of the observation of the intestinal lumen and intestinal mucosa at the same time along the intestinal lumen forward slowly through the lumen into the mirror, you can always back out of the mirror and then look for the lumen, and then into the mirror, until the end of the ileum sent to the end of the segment. The process can be supplemented with position changes and assistant pressure. If necessary, a small amount of gas injection to make the intestinal lumen open. The intestinal mucosa should be carefully observed when retracting the scope, and usually the retraction time should be more than 6 minutes to ensure the quality of colonoscopy diagnosis and treatment. If the patient appears uncomfortable symptoms, it is recommended to consult the doctor in time, the doctor according to the specific conditions, to formulate the appropriate examination and treatment program, in order to avoid delaying the condition.