Abstract: Objective To investigate the effect of fractional oral administration of sodium phosphate solution for bowel preparation before colonoscopy in children, and to observe the adverse reactions. Methods A total of 96 children underwent colonoscopy in Shengjing Hospital Affiliated to China Medical University were enrolled. Before colonoscopy, the children were taken sodium phosphate for bowel preparation. These children were divided into control group and observation group by random number table method, with 48 cases in each group. The control group was given sodium phosphate intestinal solution for one time at 4 h before examination, and the observation group was separately given the same volume of sodium phosphate intestinal solution for 2 times before examination. The intestinal cleanliness of the two groups was compared, and the occurrence of related gastrointestinal adverse reactions was recorded during the intestinal preparation. Results All the children successfully completed the intestinal preparation. The excellent and good rate of intestinal cleaning in the observation group was slightly higher than that in the control group, but the difference was not statistically significant(97.92% vs. 87.50%, P>0.05); related gastrointestinal adverse reactions occurred in both groups, but there were no significant differences in the incidences of vomiting, abdominal distention and abdominal pain between the two groups(P>0.05). However, the incidence of nausea and total adverse reactions in the observation group was 4.17% and 8.33% respectively, which were significantly lower than 18.75% and 31.25%, respectively, in the control group, and the difference - was statistically significant(P< 0.05). Conclusion Fractional oral administration of sodium phosphate solution for intestinal preparation can reduce occurrence of gastrointestinal adverse reactions, and has satisfactory intestinal cleanliness.