A method for the determination of nine nitrosamines in water by ultra performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS） was proposed.After comparison of effects on detection signals of different mobile phases,different SPE cartridges as well as different reconstitution solvents,methanol and 10 mmol/L ammonium bicarbonate water solution were selected as mobile phases.A coconut charcoal cartridge was selected as pre-treatment SPE cartridge and pure water was selected as reconstitution solvent.Based on the optimum sample pretreatment procedures and instrument conditions,standard calibration curves for the analytes were obtained.The linear calibrations ranged from 5 ng/L to 150 ng/L with correlation coefficients（r2） of 0.997-0.999.The limits of detection（LODs） and limits of quantitation（LOQs） for nine nitrosamines were in the range of 1.3-2.8 ng/L and 4.0-8.5 ng/L,respectively.The intra- and inter-day relative standard deviations（RSDs） were in the range of 3.5%-8.4% and 2.8%-7.5%,respectively.The method recoveries were in the range of 80.4%-109.6% for the three different types of water samples at two spiked concentration levels.Nine nitrosamines in drinking water from three water treatment plants as well as effluents from three wastewater treatment plants were detected.The results showed that,among the nitrosamines，the NDMA concentration was the highest,with 10.2 ng/L and 45.6 ng/L in drinking water and wastewater effluent,respectively.