Abstract: Three microcystins were determined by automatic solid phase extraction( SPE) and high performance liquid chromatography( HPLC) in this study.Instead of the traditional pretreatment methods,Reeko automatic- SPE system was used for a fast enrichment process. Samples were chromatographed isocratically using a KH2PO4( p H3.0) buffer solution- methanol mobile phase on a C18 column in- line by diode array detector. Good linear relation were presented in the range of 0.1 ~ 10.0 μg / m L for all microcystins with the correlation coefficients R2≥0.999.The detection limits of three microcystins were 0.05 μg / L( S / N = 3).Recoveries of these microcystins at three different concentration levels were studied.The recoveries of this method were 86.3% ~99.7% with a good relative standard deviations of 1.70% ~ 2.72%( n = 6). This method was easy,fast and accurate and suitable for a rapid determination of microcystins in drinking water.