A liquid chromatography-tandem mass spectrometric(LC-MS/MS) method was developed for the simultaneous determination of benzo(a)pyrene and aflatoxins(B1,B2,G1,G2) in vegetable oil.The sample was extracted with ethyl acetate-hexane(1∶1),cleared up by GPC.The separation of target compounds were performed on an XDB C18 column(4.6 mm×50 mm,1.8 μm) at 25 ℃ with methanol and 10 mmol/L ammonium acetate solution as mobile phase by gradient elution at a flow rate of 0.25 mL /min.Then the samples were ionized using atmospheric-pressure photoionization ion source ionization,examined under multiple reaction monitoring(MRM) mode and quantified by the external standard method.The quantitation limits of benzo(a)pyrene and aflatoxins(B1,B2,G1,G2)were 0.3,0.5,1.0,1.0,1.0 μg/kg，respectively.The linear ranges of benzo(a)pyrene and aflatoxins(B1,B2,G1,G2) were 0.3-25,0.5-30,1.0-10,1.0-30,1.0-10 μg/kg,respectively,with correlation coefficients(r) of 0.999 6-0.999 9.The spiked recoverie of target compounds in vegetable oil were in the range of 80.3%-106.8%，with relative standard deviations of 4.0%-10.0%.The real sample tests showed that the method was simple and accurate,and could be used for the determination of benzo(a)pyrene and aflatoxins(B1,B2,G1,G2) in vegetable oil.