Abstract: Tandem mass spectrometry has developed into a mature technology, applied to pesticides, food safety, environment, medicine and so on. Methods such as Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS) cannot meet the requirements of trace level analysis for complex samples. In this paper, the method of analysis organochlorine pesticides and polychlorinated biphenyls in plants by Gas Chromatography-Tandem Mass Spectrometry is described. According to the detection limits and qualitative and quantitative analysis of results by GC-MS-MS, Gas Chromatography-Electron Capture Detector (GC-ECD) and Gas Chromatography-Select Ion Storage-Mass Spectrometry (GC-SIS-MS), the applicability of the method GC-MS-MS was inspected through the detection of actual samples such as cabbage, spinach, carrots and oranges. The method detection limits (MDL) of GC-MS-MS were between 0.03 ng/g and 0.29 ng/g, and the MDL of the majority of compounds was lower than those by GC-ECD. The average MDL is 0.4 times lower than those by GC-SIS-MS. In this study, it was found that cabbage samples do not contain trans-chlordane analyzed by GC-MS-MS. This result eliminated the false positive detection by GC-ECD. GC-MS-MS also showed good qualitative and quantitative ability to analyze carrot samples with complex matrices, which was difficult to purify. The 0.03 ng/g HCB was detected in spinach by GC-MS-MS, which was not detected by GC-ECD. This indicates that the method of GC-MS-MS has higher sensitivity and can accurately measure trace compounds in the sample. Compared with the different results by various analysis technology including GC-ECD, GC-SIS-MS and GC-MS-MS, tandem mass spectrometry has the advantages of high sensitivity and accurate qualitative and quantitative analysis. This technology can reduce purification steps and improve analysis efficiency, which can be applied to verify the analytical results for complex samples.