The community and biodiversities of Rotifera,including species composition,density,biomass,biodiversity index and regression analysis were studied at six sampling stations(Ⅰ-Ⅵ) in the touring lakes,Ningbo.In one year study,21 species of rotifers were found.The annual average density of rotifers was 1782 ind.·L^-1;biomass was 1.330 mg·L^-1 and Margalef's biodiversity index was 0.740.Trichocerca pusilla and Polyarthra trigla were the dominant species in three touring lakes.Density and biodiversity index of rotifer in lake Dongqianhu were lower than those in the lakes Yuehu and Rihu.Regression analysis result showed that biodiversity index of rotifer had a negative linear relationship(r=-0.545,n=24,p<0.01)with water body pH value,and there was a significantly negative linear relationship(r=-0.668,n=16,p<0.01)between biodiversity index of rotifer and the community density in the lakes Yuehu and Rihu.