Lake Dishui is a man-made lake which was excavated in the reclaimed beach land, Shanghai.The study analyed monthly sampled rotifer from the lake between 2008 and 2009 to understand the dynamic features of planktonic rotifer.We also studied the specific composition, abundance and related ecological variables of rotifers.Altogether 33 species of rotifers, belonging to 12 genera were identified.The dominant species were including Brachionus calyciflorus, B.angularis, Trichocerca rousseleti and Polyarthra sp.The rotifer abundance of annual varying was 58.3-1829.2ind./L.There was an extremely significant difference among the four seasons, but no significant difference among the sample stations.Apparently the abundance of rotifers in summer and autumn was higher than those in spring and winter, particularly the value in autumn was a maximum, averaged 1087.5 ind./L, The change of rotifer-abundance was mainly related to the variables, such as Chlorophyta biomass and temperature.