Abstract: To improve the detection efficiency of polar plant growth regulators with high boiling point,a new method for the simultaneous determination of 6 carboxyl- contained plant growth regulators( indole-3- acetic acid,indole-3- butyric acid,2,4- D,α- naphthaleneacetic acid,gibberellic acid and 4- chlorophenoxyacetic acid) residues in vegetables was developed by Qu ECh ERS- ultra performance liquid chromatography- tandem mass spectrometry( UPLC-MS/MS). The analytes were extracted with acetonitrile containing 1% acetic acid,and salted out with anhydrous magnesium- sodium chloride. The extracts were cleaned up by dispersive solid phase extraction( d-SPE) using anhydrous magnesium- graphitized carbon black( GCB) as sorbents. Chromatographic analysis was carried out on BEH C18column( 50 mm × 2.1 mm,1.7 μm) using a mobile phase comprised of acetonitrile and water( containing 0.01% acetic acid) in gradient program. The plant growth regulators were analyzed by negative electrosprary ionization( ESI-) tandem mass spectrometry under multiple reaction monitoring( MRM) mode.Quantification was achieved using matrix- matched external standard method.The calibration curves showed good linearity in each concentration range,and the recoveries of the 6 plant growth regulators spiked at three levels in cucumber and tomato were between 81.6% and 108%,with the relative standard deviation( RSD) ranging from1.3% to 8.4%.The limits of detection( LODs) in vegetables were in the range of 0.5 μg / kg and 6 μg / kg.The method is simple,convenient,time- saving,sensitive and accurate,and suitable for the rapid determination of plant growth regulators residues in vegetables.