The analysis of pesticides in water samples is a problem of primary concern to quality control laboratories due to the toxicity level of these compounds and their public health risk.A method for the analysis of eight phenoxy acid herbicide residues in water was developed using solid phase extraction(SPE) combined with ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The water samples were extracted and cleaned with HLB SPE column.The extract was separated on a BEH C18 column using acetonitrile-2 mmol/L aqueous ammonium acetate as mobile phase with a linear gradient elution program,and analyzed by MS under negative ion mode with multiple reaction monitoring(MRM) mode.The calibration curves of eight phenoxy acid herbicides were linear in the concentration range of 0.8 -100 μg/L,with correlation coefficients of 0.995 8-0.999 6.The spiked recoveries ranged from 74% to 90%,with relative standard deviations of 1.0%-12.0%.The detection limits(3S) were between 1.0 ng/L and 1.8 ng/L.The method was simple,rapid,sensitive and accurate,and was suitable for the simultaneous determination of eight phenoxy acid herbicides in surface water and waste water.