Objective In order to establish a method to identify chemical poisoning with an food poisoning incident as an example. Methods Sixteen organophosphorus and twelve carbamate pesticides was detected in 6 suspected samples using of 4000 QTRAP liquid chromatography-tandem mass spectrometry with EPI scan mode. Results The toxic substance carbofuran was detected in the vegetables and liver samples, and was not detected in the other four samples. No organophosphorus pesticides and other 11 carbamate pesticides were detected in all samples. Conclusion This food poisoning incident was caused by carbofuran. The establishment of a sensitive, rapid and accurate liquid chromatography-tandem mass spectrometry detection method and mass spectrometry database in the laboratory was of great significance for dealing with emergency events.