Objective To identify the suspected food, pathogenic factors and risk factors of the foodborne disease outbreak in a school, and to provide reference for the prevention, control and investigation of similar events in the future. Methods Descriptive epidemiological method were used to analyze the clinical characteristics, epidemiological characteristics and related risk factors of the cases. Suspicious meals and food were identified by case-control study. Samples such as anal swabs of cases and kitchen workers, reserved food and environment were collected for etiological detection. Salmonella isolates were classified by pulsed field gel electrophoresis. Results A total of 74 cases were found, with an incidence rate of 1.9%. The main clinical symptoms were diarrhea (83.8%), abdominal pain (78.4%) and fever (63.5%). The prevalence curve showed intermittent homologous exposure, and the distribution of cases in classes and dormitories showed no obvious aggregation. Results of a case-control study showed the risk factor was the rice with scrambled egg from the second dining hall (October 8 OR=7.00,95%CI: 1.51~32.48; October 9 OR=262.50, 95%CI: 22.21~3 102.06). A total of 76 samples were collected, 12 of which were isolated and cultured for Salmonella enteritidis. There are two zonal types with similarity of 95.7% by PFGE analysis. Conclusion This incident was a foodborne disease outbreak caused by Salmonella enteritidis, and suspected food was the rice with scrambled egg. Food hygiene supervision should be strengthen in schools and other collective units, and food with eggs should be thoroughly cooked.