To determine thetoxins and its contentsin food poisoningrapid and accurate, and to provide a scientific basis for emergency response. MethodsAccording to the epidemiological investigation guide of food safety accidents and the trade standard of watermelon (NY/T 584-2002), multiple methods were used for three suspected watermelon samples sent by local CDC. ResultsHigh concentration of aldicarb including aldicarb sulfone and aldicarb sulfoxide were detected in watermelon.ConclusionThis food safety accident was caused by aldicarb.