Eutrophication　of　fresh　water　lakes　and　ponds　has　caused　the　occurrence　of　cyanobacteria.　Microcystins　(MCs)　is　a　class　of　toxic　cyclic　heptapeptide,　which　may　be　produced　by　some　strains　of　various　blue-green　algae.　It　has　become　potential　hazardous　material　in　aquatic　environments　for　its　toxic,　distribution　and　stability.　MCs　has　been　showed　to　be　extremely　potent　hepatotoxins　and　been　viewed　as　a　promoter　of　liver　tumor.　In　this　review,　the　pollution　condition　of　MCs　and　its　hepatotoxins　as　well　as　its　mechanisms　have　been　summarized.