【Abstract】 Objective To identify the epidemiology of human calicivirusrelated diarrhea of children under 5 years old in Chengdu and discuss clinical safety and efficacy of ORS III on calicivirus diarrhea in hospitalized children. Methods RTPCR was used to detect the virus from stool specimens. The positive cases of calicivirusinfected children were divided into group A treated with ORS III and group B treated without ORS III. The clinical safety and efficacy were observed. Results 1064 specimens were collected from children suffered with diarrhea. The annual detection rate 2012, 2013 and 2014 were 284%, 216% and 271%, respectively. There were no significant differences in the number of days of diarrhea and the number of diarrhea before hospitalized. There was significant difference between the two groups in the time of diarrhea remission, the time of dehydration correction, the amount of intravenous infusion and the concentration of sodium and sodium in the 24 hours after admission. After the use of ORS III, the time of dehydration correction was shortened and the amount of intravenous infusion was significantly reduced after 24 hours. Concentration of serum sodium was higher than that of unused children, but still within normal range. There was no significant difference in serum potassium concentration and hospitalization time between the two groups. Conclusion Human calicivirus has become one of the leading pathogens that contributed to diarrhea of children under age 5 in Chengdu. ORS III treatment of calicivirus diarrhea hospitalized children can help shorten the course of diarrhea, dehydration correction time and reduce the amount of intravenous infusion 24 hours after admission.