Abstract: Objective To find out the risk factors of Salmonella outbreak in a school, and to put forward prevention and control measures. Methods Descriptive epidemiology study was performed to survey the basic hygiene conditions of the school. Case control study was conducted to investigate the suspected meal and food through questionnaires. Specimens from patients, culinary workers, residual foods and environment samples were collected for pathogenic isolation, serotype and pulsed field gel electrophoresis (PFGE) molecular classification. Results First case’s onset date was June 9 and last case’s was June 12. The outbreak lasted 4 days. Epidemiological curve suggested that it be a point source outbreak. A total of 61 cases were identified and were all boarding students, including 12 males and 49 females. The incidence of female (10.7%, 49/460) was significantly higher than that of males (3.9%, 12/309) (P<0.01). Case control study indicated that the egg sandwich of breakfast on June 9 was the risk factor to cause this outbreak (OR=21.70，95% CI:-8.50－55.50). A total of 25 strains of Salmonella enteritidis were isolated and identified, of which 19 were from anal swabs of 25 patients, 5 from anal swabs of 14 canteens kitchen staff, and 1 from 11 swabs of refrigerator handles, respectively. PFGE analysis showed that all the 25 strains had the same PFGE type. Conclusion This was a foodborne disease outbreak caused by Salmonella enteritidis and the risk factor was egg sandwich of breakfast. Health supervision and inspection authorities should pay much attention to all kind of food with eggs as the raw material.