Abstract: OBJECTIVE To establish a method for the determination of 15 organophosphorus pesticides in castor oil by GC-MS. METHODS The determination was performed on VF-1701MS quartz capillary column(30 m×250 μm, 0.25μm). The column was subjected to temperature programming, the injector temperature was 270℃; the flow rate was 1.0 mL·min^-1; the injection volume was 1.0 μL; the carrier gas was high purity helium and it was splitless. RESULTS The mass concentration of 15 organophosphorus pesticides had good linear relationships in the range of 0.005-0.5 mg·L^-1, and the correlation coefficients were over 0.998 9. The method detection limits were 1-13 μg·kg^-1, the average recoveries at 50, 100, 200 μg·kg^-1 level was 85.3%-102.1%, 86.4%-107.0%, 88.3-109.3%, respectively. The RSD of the determination results were 1.7%-6.0%(n=6). CONCLUSION This method is easy, fast and effective, which reduced the maintenance cost and pre-treatment time of the experiment. The method was well suitable for the analysis of multi-organophosphorus pesticides in castor oil.