To find out the scale of the epidemic and the pathogenic source of a food poisoning incident at a kindergarten in Shenzhen, and provide recommendations for the prevention.Methods The cases were screened according to the case definition. The descriptive epidemiology was used to address epidemiologic characteristics and provide clue for etiology of the disease, while case-control study was used to analyze the risk factors. The food samples, vomitus, anal swabs and environment samples were collected for microbiological testing. The cognition of vendors and consumers to bitter Lagenaria siceria was investigated at the market. Results A total of 21 cases with clinical symptoms:vomiting (80.95%, 17/21),diarrhea (71.42%, 15/21), abdominal pain (61.90%, 13/21), dizziness (28.57%,6/21) and headache(14.29%,3/21) were found. The shortest, longest and median incubation period was 0.5,7.5,2.5 hours, respectively. The diet history of 42 control cases was investigated. Case-control study showed that the Lagenaria siceria was the suspicious food (OR=266.00,CI=14.15-5 000.00). Staphylococcus aureus, Bacillus cereus, Salmonella, Shigella, Vibrio parahaemolyticus and Proteus were not detected from 22 samples. In addition, the remaining lagenaria siceria tasted very bitter. Only 19.05% (4/21) of the vendors and 5.77% (3/52) of the residents knew that the bitter Lagenaria siceria could cause food poisoning.Conclusion The food poisoning incident was caused by bitter Lagenaria siceria. It was suggested childcare facilities should use other vegetables instead of Lagenaria siceria dishes and consumers should taste the Lagenaria siceria before buying it. At the same time the health sector should strengthen the health education of merchants and citizens to prevent the poisoning.