Abstract: A method based on ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established for the simultaneous determination of eight cannabinoids in cannabis plants. The sample was extracted with methanol. Using CHIMADZU Shim-pack Velox PFPP chromatographic column, gradient elution with 20 mmol/L ammonium acetate, 0.1% formic acid buffer and acetonitrile as mobile phases, electrospray ion source positive and negative ion multi-reaction monitoring were used for mass spectrometry analysis, and the external standard method was used to quantitatively analyze the eight cannabinoids in cannabis plants. The eight cannabinoids have good linearity in the linear range of 5～500  μg/L, and the limit of detection (LOD) and limit of quantification (LOQ) are 0.13～1.26  μg/L and 0.39～3.83  μg/L, respectively. The relative standard deviations of retention time and quantitative ion peak area are 0.10%～0.43% and 3.46%～13.41%, respectively. The UPLC-MS/MS technology of cannabinoid quantitative analysis method show high sensitivity, good reproducibility and high analysis efficiency, and can be used to detect cannabinoid content in cannabis plant.