Objective The new method of re-evaluation of drugs in bowel preparation , to explore an effective bowel preparation medication and measures to improve the success rate of colonoscopy and treatment . Methods Between January 2011 and December 2012 , 85 simple colon polyps patients were recruited . According to the principles of self-control design , cases were received 3 times of colonoscopy , and they were divided into 3 groups according to the bowel preparation medication: group A ( 20% Oral Mannitol group ) , group B ( oral 50%magnesium sulfate group ) , group C ( orally taken Senna group ) .3 groups of patients after intestinal cleanliness were investigated with Boston bowel preparation scale .Results PPBS scores after left colon, transverse colon, right colonand the entire colon intestinal cleansing effects of the three groups , while the differences were no statistically different ( H =1.103, 1.377, 0.179, 0.160, respectively;P >0.05 ). Conclusions Oral administration of 20%mannitol,50%magnesium sulfate, and senna bowel cleansing has no significantly difference in bowel cleansing . Care and health education are important factors for intestinal cleansing of bowel preparation .