Abstract: From March 26 to April 1 2012, an outbreak of infectious diarrhea caused by water contamination occurred in Jiugu middle school in Susong country, Anhui province. A total of 196 cases were reported with an attack rate of 8.78%. Etiological detection indicated that the pathogen was Enterotoxigenic Escherichia coli. The epidemic was effectively controlled after taking appropriate measures of interrupting transmission, wiping out transmission factors and health education.