Objective To investigate and analyze the epidemiological characteristics of suspected milk poisoning, identify the causes of food poisoning incident, and provide the reference for similar food poisoning emergencies. Methods According to the field epidemiological investigation, the samples were tested by high performance liquid chromatography, and the causes of food poisoning were determined by comprehensive analysis. Results Twenty eight people were poisoned, sodium dehydroacetate was detected in the milk samples tested, the content was 1.70 and 1.71 g/kg, and no other toxic substances were found. Conclusion The poisoning was caused by the illegal addition of high concentration sodium dehydroacetate in milk.