Abstract：Objective To understand microcystins（MCs）pollution in important waters of Shaoxing，so as to provide evidence for risk assessment and supervision of water quality safety.Methods Water samples were collected from 15 points set in three Shaoxing waters during September 2016 to September 2017. Six kinds of MCs（MC-LR，MC-RR，MC-YR，MC-LA，MC-LY，MC-LF）in samples were detected by ultra performance liquid chromatography tandem mass spectrometry，and the results were compared according to different time and place.Results MCs were detected positive in 22 of the 135 samples ，the total detection rate was 16.3%.The detection rates of Xiaoshao River，Puyang River and Cao′e River were 7.9%，18.5%和26.7% respectively; the detection rates in July，August and September were 13.3%，40% and 46.7% respectively，and the other months were not detected. In 22 positive samples，the detection rates of 6 MCs from high to low as follows: MC-LR（100%），MC-RR（100%），MC-YR（22.7%），MC-LY（18.2%），MC-LF（13.6%）and MC-LA（0%）.Conclusion In the three important waters of Shaoxing，microcystins were polluted in summer and autumn，which were mainly MC-LR and MC-RR.
