Find out the reason of food poisoning and take effective control measures to prevent similar incidents.Methods Use descriptive epidemiological curves to deduce suspicious meal, identify suspicious meal and suspicious foods from case-control study, analyze the dose-response relation between food and disease, and collect related samples of for laboratory test. Results The reason of the food poisoning was the dinner on August 15th. There was dose-response relation between fried mackerel consumption and morbidity (trend chi-square test P<0.05). The histamine content of the remaining fried mackerel exceeded the national standards.Conclusion Consumption of fried mackerel was the main reason of histamine food poisoning.