A method based ongas chromatography-tandem mass spectrometry (GC-MS/MS) was developed for the determination of nonylphenol (NP) in vegetable oil. The oil sample was extracted by ocean eddies with acetonitrile as solvent and purified by dispersive solid phase extraction. The results showed agood linear relationship when the content of nonylphenol was in the range of 0.02～1mg/L, correlation coefficient was 0.9992, The recovery rate on 0.02mg/kg ，0.06mg/kg and 0.2mg/kg were in the rage of 82.3%～94.7%. The limit of detection was 0.02mg/kg.