A liquid chromatography-tandem mass spectrometric（LC-MS/MS) method was established for the determination of tebufenozide,aldicarb,aldicarb sulfoxide and aldicarb sulfone in scallion.The samples were extracted with acetonitrile and ethyl acetate,respectively.It was found that the extraction efficiencies of 4 pesticides with acetonitrile were better than those with ethyl acetate.Co extractives were removed from the acetonitrile extracts using dispersive solid phase extraction（DSPE).The calibration curves were linear in the range of 10-120 μg/L with correlation coefficients（r2) more than 0.995.The limits of quantitation（LOQs)of 4 pesticides were all less than 10 μg?kg-1,and the average recoveries at the spiked level of 10 μg?kg-1 in scallion samples ranged from 60% to 110% with RSDs less than 5.0%.The results showed that this method was rapid,sensitive and specific,and was appropriate for the simultaneous identification and quantification of 4 pesticides in scallion.