There are two clinical approaches to bowel cleansing, a cleansing enema and an oral laxative bowel cleansing. The former mostly gives saline or warm soapy water for anal injection, which is injected through the anal canal pressure and then addresses the pressure in the lower gastrointestinal tract, especially in the sigmoid colon, rectum or part of the descending colon, relieving intestinal constipation and acting as a partial bowel cleansing. The most common method of bowel cleansing is the oral administration of compound polyethylene glycol electrolyte dispersion, magnesium sulfate or mannitol, etc. After oral administration, patients drink a lot of sugar saline or plain water, and the drug acts as a cleanser for the entire intestine through flushing, solving the problem of dry stools, and is also a method of colonoscopy to cleanse the intestine and help observation, which is the most commonly used method in clinical practice.