Objective:A detection method was developed for benazolin residual in rape and rapeseed by High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).Methods:The rape and rapeseed were extracted with acetonitrile reagent, purified by Pesti Carb-NH2, separated by C18 column, carried out with methanol-ammonium acetate aqueous solution, detected by HPLC-MS/MS.Results:The liner relation was good in the ranger of 0.01~1.00 μg/mL, and the coefficient of determination was 0.999, the limit of detection(LOD) was 0.008 mg/kg, with the limit of quantification (LOQ) of 0.027 mg/kg. At the spiking levels of 0.03, 0.06, 0.15 mg/kg, the recovery rate of the method was 73.3%~91.3%, and RSD was 4.4%~8.1%.Conclusion:The presedent treatment method is easily-conducing, efficient, and highly sensitive and selective, and it can be used to determine benazolin in rape and rapeseed.