The community structure of Rotifera and ecological assessment of water quality were studied by investigating the species composition,density seasonal dynamics,biodiversity and Q_B/T index in the sampling stationsⅠ-Ⅵof Jinshuitan Reservoir,Zhejiang. During one year study,45 species of Rotifera were found,and 37 species were pollution indicator species,of which oligo-Pmesosaprobic,β mesosaprobic andβ-amesosaprobic species accounting for 32.4%,35.1% and 24.3% of the total indicator species respectively.The dominant species were Keratella cochlearis,Polyarthra trigla and Trichocerea similis.Community density of Rotifera ranged from 4.8 to 542.5 ind·L^-1,with an average of 135.7 ind·r^-1;Shannon-Wiener index(H^T) ranged from 2.60 to 3.65,with an average of 3.20;QB/T value ranged from 0.83 to 2.50,with an average of 1.39.Rotifera density and H' value were lower,but Q_B/T value was higher in the stationsⅠ-Ⅱ than in the stations Ⅲ-Ⅵ.Q_B/T value decreased with the increasing of water transparency.Jinshuitan Reservoir was in oligo-mesosaprobic status,of which stationsⅠ-Ⅱ were mesosaprobic,while stations Ⅲ-Ⅵ were oligo-βmesosaprobic.