In order to understand the status of rotifer community and the relationship with water quality, the rotifer community and water quality status in Dishui Lake river system of Shanghai were monthly studied from January to December in 2010. There were six and five sampling points in the priming river course and the lake area, respectively. 35 species of rotifers belonging to 7 families and 19 genera were identified. The dominant species were Polyarthra trigla, Trichocerca pusilla, and Anuraeopsis fissa. The uniform annual values of rotifer density and biomass in the priming river course were 821.31/L and 600.97×10^-3mg/L, respectively; and the same values in the lake area were 434.98/L and 317.74×10^-3mg/L, respectively. Annual means of Margalef diversity index in the priming river course and the lake area were 1.87±0.19 and 1.14±0.23, respectively. Annual means of Shannon-Wiener diversity index in the priming river course and the lake area were 1.58±0.25 and 1.21±0.76, respectively. Density, biomass, and diversity index of rotifers in the priming river course were higher than that in the lake area. Seasonally, rotifer density was significantly positively correlated with the value BOD₅ and a most significantly positive correlation between rotifer biomass and BOD₅ was also detected in the priming river course. There was a significantly positive correlation between the rotifer density and water temperature in the lake area and the correlation between the biomass and water temperature was most significantly positive. Horizontally, the annual mean of rotifer biomass was significantly negatively correlated with the total dissolved salt and pH, while it was significantly positively correlated with NO₂-N, and also had a most significantly positive correlation with BOD₅. Water quality of Dishui Lake river system was evaluated considering indicator organisms, species diversity index, and physicochemical factors of the water. The results show that lake area is in the light eutrophication level and priming river course is in the light-middle eutrophication level in the year of 2010.