Colonoscopy examination is the gold standard for diagnosis and treatment of colon diseases and screening for early cancer. Good quality of bowel preparation, which is also called intestinal cleanliness, is the prerequisite for full visualization of colonic mucosal lesions and their details. In clinic, more intestinal cleansing agents, such as polyethylene glycol and magneium suifate, have bad taste and high dosage, which can not be tolerated by some patients and affect the effect of bowel preparation. The use of oral adjuvant, add adjuvant to intestinal cleansing agents, new low-volume or very low-volume polyethylene glycol-ascorbic acid preparation methods, can reduce the incidence of adverse reactions, such as nausea and vomiting in patients, improve their tolerance, satisfaction and so on. This article reviews the methods of improving the taste and reducing the adverse reactions of intestinal cleansing agents at home and abroad to offer references for clinical practice.