Bowel cleansing is required prior to colonoscopy, and alternatives to electrolyte water cleansing include senna, magnesium sulfate, mannitol, lactulose, and a newer class of compounded sodium picolinate, but each has its own advantages and disadvantages. Enteroscopy is an invasive operation, intestinal cleanup is more helpful to the physician to check whether there is a lesion and to take material. Senna and magnesium sulfate, which were used in the early days of colonoscopy, are no longer widely used due to poor results in some patients. Mannitol laxation may produce gas, common examination process usually do endoscopic electrocautery, electrocoagulation and other operations, this may be dangerous, so the current application of mannitol is rare. Lactulose can also be used as a bowel cleansing agent, but the effect varies from person to person. Compound Polyethylene Glycol Electrolyte Bulk is the most commonly used laxative, which contains electrolytes formulated according to the formula, so that when patients take it, electrolyte disorders rarely occur, and the drug has few side effects, and has little effect on elderly patients and liver and kidney function. However, the drug needs to be diluted with a large amount of water and taken with a poor taste, and some patients may experience nausea and vomiting after taking it. The newer class of laxatives such as Compound Picolinate Sodium Sulfate, which is taken in smaller doses and can be taken with additional water, is also a good choice. The choice of laxatives should be used under the comprehensive assessment and guidance of the physician to avoid incomplete cleansing affecting the test results.