Abstract: OBJECTIVE To investigate the epidemiological characteristics and pathogenic factors for norovirus infection in a school so as to provide data support and theoretical basis for taking effective prevention measures.METHODS From Jan 18, 2021 to Jan 19, 2021, more than 20 students in a school of Shandong province had symptoms of fever, abdominal pain and diarrhea. After receiving the notice, the author and others went to deal with it in time, and all 477 students in the department were included in the survey. The cases were clearly defined, the unified epidemiological questionnaire was used, the epidemiological survey was also conducted for the cases and their close contacts based on the interview outline, the key information such as the diet history before the onset, disease time and clinical symptoms were recorded in detail. The vomits, anal swabs and foot reserved samples were detected by using real-time fluorescence quantification polymerase chain reaction（PCR）. Excel 2010 was used for data entry and statistical analysis, and the characteristics of distribution of time, space and population were analyzed by descriptive epidemiological method.RESULTS This was a person-to-person spread cluster outbreak caused by norovirus infection. The food-borne and water-borne factors were excluded. A total of 41 cases were confirmed, with the attack rate 8.60%（41/477）, 14 of whom were diagnosed by clinical laboratory test, 27 were clinically diagnosed. Besides, there were 28 patients with general discomfort. The epidemic was quickly and effectively controlled by taking targeted prevention and control measures such as timely isolation of patients, good environmental disinfection and protection of susceptible population.CONCLUSION This is a person-to-person spread cluster outbreak caused by norovirus infection. It is suggested that the construction of health facilities of the school should be strengthened, the health system should be strictly implemented, the personal health habits should be developed so as to achieve the key prevention of frequent diseases, early prevention in high incidence season and special prevention of key groups.