The invention provides an LC-MS/MS method for detecting IPP, GPP, FPP and GGPP in a fresh tobacco leaf. The LC-MS/MS method comprises the following steps: 1) preparing an extraction solvent; 2) conducting liquid nitrogen flash freezing on the fresh tobacco leaf, and conducting freeze drying and crushing; 3) adding the extraction solvent to the crushed sample, and conducting ultrasonic extraction at low temperature; 4) carrying out refrigerated centrifugation, taking supernatant, and filtering; 5) conducting LC-MS/MS method to detect IPP, GPP, FPP and GGPP in the detected sample. The LC-MS/MS method has the advantages that the pretreatment method of the sample is simple and only comprises ultrasonic extraction and filtration; compared with the existing method, the method is high in sensitivity, good in precision, and high in recovery of standard addition; the sample can be directly fed and analyzed through filtration, but according to the methods in the existing documents, the pretreatment method is complicated and time-consuming, and requires pyrophosphatase and alkaline phosphatase for carrying out biochemical reaction on the sample. Therefore, the LC-MS/MS method disclosed by the invention can effectively increase the analysis efficiency, and is suitable for analysis of the ultralow content target in the complex substrate.