A method was developed for the determination of paraquat and diquat residues in water by high performance liquid chromatography-tandem mass spectrometry with solid phase extraction.The samples were cleaned up by Cleanert PWCX solid phase extraction,separated on a HILIC column using acetonitrile-5 mmol/L ammonium acetate（pH 37 with formic acid） as mobile phase by gradient elution,then detected in SRM mode and quantified by external standard method with the matrix matched calibrations.The calibration curves for paraquat and diquat showed good linearities in the concentration ranges of 100-2000 μg/L and 10-2000 μg/L,respectively,with correlation coefficients（r2） no less than 0997.The average recoveries for paraquat and diquat in agricultural environmental water at spiked levels of 30-200 μg/L were in the ranges of 968%-1258% and 972%-1182%,with intra assay relative standard deviations（RSDs） of 30%-63% and 29%-60%,and inter assay relative standard deviations of 33%-82% and 27%-79%,respectively.The limits of detection（LODs） and quantitation（LOQs） of the method were 50 μg/L and 03 μg/L,and 100 μg/L and 10 μg/L,respectively.The results indicated that the developed method is easy,fast and sensitive,its indicators such as the linear range,recovery,precision and detection limit could meet the requirements for residue analysis.The method is suitable for the determination of paraquat and diquat in agricultural environmental water