The process of doing colonoscopy mainly includes pre-colonoscopy examination, bowel preparation, colonoscopy examination, post-examination precautions and receiving the report. 1. Pre-colonoscopy examination: If painless colonoscopy is performed, electrocardiogram examination is required, etc. Those with basic cardiopulmonary diseases are also required to undergo pulmonary function test, electrocardiogram, cardiac ultrasound and other examinations. 2. Bowel preparation: 3 days before the examination, you should eat semi-liquid food, avoid vegetables and other fiber-rich food, 1 day before the examination, you should eat liquid food, and take intestinal cleansing medication such as polyethylene glycol electrolytes the night before the examination or about 6 hours in advance until the bowel movement shows a clear watery pattern. 3. Colonoscopy: Painless colonoscopy will be performed with general anesthesia before the start of colonoscopy. The enteroscope will be pumped into the intestine after sufficient lubrication, and the endoscope will be extended from the anus into the rectum, sigmoid colon, descending colon, transverse colon, ascending colon, and up to the ileocecal valve, and in the process of backing out of the mirror, it will observe whether there is any lesion according to the intestinal partition, and pump out the pumped-in gas. 4. Post-examination precautions: water and food can be consumed without discomfort after colonoscopy, and spicy and stimulating foods should be avoided within 24 hours. No driving, riding, etc. are allowed within 24 hours after the painless colonoscopy. 5. Receive the report: the report of colonoscopy itself can be received after the examination, if there are polyps in the process of colonoscopy, such as resection biopsy needs to receive the pathology report after about a week. It is recommended that patients follow the doctor’s instructions for bowel preparation and related examinations before the colonoscopy, use medications under the guidance of the physician, cooperate actively during the examination, pay attention to the results of the report after the examination, and consult with a specialist in a timely manner.