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A method based on solid phase extraction combined with ultra-performance liquid chromatography- tandem mass spectrometry (SPE-UPLC-MS/MS) was established for the simultaneous determination of thirty- five pesticides and transformation products of high concern with different polarities at trace level in environmental waters. Under optimized conditions, tandem cartridges with Oasis HLB column and activated carbon were used for the enrichment of water samples. HLB column was eluted by 10 mL of acetonitrile, and activated carbon cartridge was eluted by 10 mL of methanol solution containing 20 mmol/L ammonium acetate. The elution solvents were mixed, concentrated and reconstituted. Finally, the elution solvent was reconstituted with a mixed solution of acetonitrile and water (1:1, V/V) containing 10 mmol/L ammonium acetate. The targets were separated by gradient elution with 5 mmol/L ammonium formate buffer and acetonitrile as mobile phases, and detected by MS/MS in the multi. reactions monitoring (MRM) mode. Under the experimental conditions, good linearity ranging from 0.5-200 mu g/L was made (R-2 >= 0.9802), and the limits of detection (LODs) were from 0.01 ng/L to 0.8 ng/L. Recoveries of most targets were 60%-120%. The SPE-UPLC-MS/MS method established here is reliable and can be applied to determine ng/L level of pesticides and transformation products with different polarities in surface water.