【Abstract】 Objective To compare the effect of the colonoscopy preparation and the adverse reactions with different use way of sodium phosphate lavage solution. Methods From May to June in 2016, we equally and randomly divided 160 patients needed colonoscopy into the observation group and control group. The patients in the observation group took orally the first bottle of sodium phosphate lavage solution at 16:00 before the operation day, and the second one at 5:00(examination in the morning) or 9:00(examination in the afternoon).And the other group took the two bottles at 4:00 and 5:00(examination in the morning) or 8:00 and 9:00 (examination in the afternoon) respectively on the day of the examination. After the colonoscopy, we compared the effect of cleanliness and adverse reactions between the two groups. Result The intestinal cleanliness of the observation group was better than that of the control group(χ2=7052，P=0008), with the lower adverse reaction rate (χ2=29330，P＜0001）。Conclusion For the colonoscopy patients, the way that took the sodium phosphate lavage solution in two days, which has better effectiveness, safety and compliance for the patients, is worthy for promotion.