Abstract: Objectives An ultra-performance liquid chromatography-tandem mass spectrometric method (UPLC-MS/MS)was established for the simultaneous determination of chlorpyrifos, butachlor, acetochlor, dichlorvos, atrazine and carbendazim residues in drinking water.Methods Water samples were separated by a Acquity UPLC BEH(2.1mm×50 mm)C₁₈ column with a gradient elution of acetonitrile/methanol and 0.1% formic acid, and detected by UPLC-MS/MS. The identification was achieved by eletrospray ionization (ESI⁺)in multiple reactions monitoring (MRM)mode.Results There was a good linear relationship while the levels of chlorpyrifos and dichlorvos were 2.5～100 μg/L, the levels of butachlor and acetochlor were 0.5～20 μg/L, the levels of atrazine were 0.125～5 μg/L and that of carbendazim were 0.05～2 μg/L in tested samples; the correlation coefficients were not less than 0.999. The detection limits were 7, 21, 10, 5 and 1 ng/L for chlorpyrifos, butachlor, acetochlor, dichlorvos, atrazine and carbendazim, respectively. The recoveries were in the ranged of 84.7%~105.0% with relative standard deviations of 1.5%～6.1%. The results indicated that the method was easy, rapid, efficient, and suitable for simultaneous determination of six pesticide residues in drinking water. Atrazine was detected in all 7 underground water samples by the method, and the concentration was 0.01～0.03μg/L.Conclusions The method was simple and rapid with good accuracy and high sensitivity. The method could meet the needs for the determination of these 6 pesticides in drinking water.