Objective To identify the causes and suspected risk factors of the food poisoning incident, provide evidence for control measures, and provide reference for the investigation and prevention of similar food poisoning. Methods The case investigations and on-site hygiene surveys were carried out by actively searching for cases through epidemiological and laboratory testing techniques. Then, the relevant food, external environment and case samples were collected for laboratory testing to determine the suspicious meals and food of this event. Results A total of 21 cases(including 2 confirmed cases) were screened out. The attack rate of this event was 12.96%(21/162), and the main clinical symptoms were vomiting (95.24%,20/21), abdominal pain (66.67%,14/21), nausea (66.67%,14/21) and diarrhea (57.14%,12/21). Data from the case control studies result showed that the suspected food was the rice left over from the dinner on October 16th (OR=18.18,95%CI: 2.05-161.38). Two cases were detected Staphylococcus aureus and enterotoxin type B in an anal swab and vomit. Conclusion The cause of this food poisoning outbreak was the leftover rice from the canteen on the 16th dinner, which was contaminated by Staphylococcus aureus and enterotoxin type B. Rice was placed at room temperature for about 5 hours and was not heated thoroughly before eating, which was a risk factor for this event. Food safety supervision and food safety education for canteen employees should be further strengthened to improve food safety awareness and prevent similar incidents.