A method based on centrifugal ultrafiltration combing with ion chromatography－triple quadrupole mass spectrometry（IC－MS） was established for the simultaneous determination of ethephon and 2，4-dichlorophenoxy－acetic acid（2，4-D） in vegetables．Four vegetables，i.e eggplant，tomato，corn and chili were pulped with a homogenizer．The samples were purified by centrifugal ultrafiltration with a 0.22 μm inorganic syringe filter．The separation of ethephon and 2，4-D were carried out on an IonPac AS19 analytical column by isocratic elution with 60.0 mmol/L KOH as mobile phase．After reducing the conductance with an in-line suppressor，the target compounds in the eluent were detected by MS with negative electrospray ionization under multiple reaction monitoring（MRM） mode，and quantified by the external spiked method．The results showed that the calibration curves were linear（,r, ≥ 0.999 5） in the range of 0.5－200.0 μg/L．The limits of detection for ethephon and 2，4-D were 0.2 μg/L and 0.05 μg/L，the limits of quantitation were 0.7 μg/L and 0.17 μg/L，respectively．The average recoveries for ethephon and 2，4-D in four vegetables were in the range of 88.3%－96.8% and 92.5%－102%，with intra-RSDs（,n, = 6） of 2.6%－5.9% and 1.2%－4.4%，and inter-RSDs（,n, = 6） of 2.2%－5.4% and 1.1%－3.4%，respectively．Furthermore，the established method was successfully applied to the determination of the pesticides in 4 vegetable samples purchased from local markets in Nanjing．Both ethephon and 2，4-D were detected with contents of 17.5－412.6 μg/kg and 1.1－4.1 μg/kg，respectively．The results showed that the method could meet the requirements for the simultaneous and rapid determination of ethephon and 2，4-D in vegetables，and provide a guidance for the detection of food safety cases in actual combat of public security.