Objective To explore the epidemiological characteristics of norovirus gastroenteritis outbreak in a study group,and take targeted control measures to avoid the spread of the epidemic and the recurrence of similar events. Methods We carried out case search according to the case definition,carried out case investigation and case-control study by using questionnaire stars,and collected vomitus,anal swabs and food samples for real-time fluorescent quantitative PCR detection to determine the pathogen. Results A total of 135 suspected cases were found in the epidemic and the onset time was concentrated,while the clinical manifestations were mainly nausea,vomiting,abdominal pain and diarrhea.27 samples (20 samples of human biological samples,3 water samples and 4 environmental smear samples) tested positive for nucleic acid of norovirus.All the suspected cases had a comma experience of eating together in a restaurant for lunch on November 17,and the norovirus nucleic acid test results of three employees in the restaurant were positive.Using contaminated outdoor well water to clean dishes and tableware may be the main cause of the diarrhea outbreak caused by norovirus. Conclusion This incident is an outbreak of infectious diarrhea caused by norovirus due to common dietary exposure.