Objective: To investigate an acute gastroenteritis outbreak caused by Norovirus, and to provide evidence for effective school infectious outbreak prevention and control. Methods: In March 2019, basic information of Huzhou Normal University and related data of cases were collected. Epidemiological characteristics were analyzed. Anal swabs of the 10 cases were collected for laboratory detection. Case definitions, specific detection criteria and procedures were based on the Diagnostic Criteria for Infectious Diarrhea (WS 271-2007) and the Technical Guidelines for the Investigation, Prevention and Control of Outbreaks of Norovirus Infection (2015 edition). Results: During March 15 to March 20, a total of 13 (12 girls and 1 boy) confirmed cases were reported, all of them were from the same class, with the incidence rate being 25.00% (1/4) and 37.50% (12/32) in boys and girls, respectively. No significant sex difference was found ( χ 2=2.05， P >0.05). Anal swab specimens of 10 students were collected from laboratory were positive for Norovirus GII and have an identity of 100%. Conclusion The gastroenteritis outbreak was deduced to be attributed to GII Norovirus infection, which are likely caused by fecal contamination through person to person contact. It is suggested that schools should strengthen knowledge education on the prevention and control of infectious diseases and improve the protection awareness and ability of teachers and students to protect them.