Community structure of rotifers and water physical-chemical factors of Danjiangkou Reservoir were seasonally investigated during July 2007 to May 2008. Seasonal dynamics of rotifer community and the water trophic and health state from the reservoir were analyzed and assessed. There 62 species were found, 30 species in Danjiang area, 54 species in Hanjiang area, and 22 species were in both places. Polyarthra vulgaris, Keratella cochlearis, Synchaeta oblonga, Trichocerca similes, Trichocerca lophoessa and Anuraeopsis fissa were the most common dominant species. Average density and biomass of rotifers reached the maximum in winter and followed by spring, summer and autumn. The changes of convergent areas are greater in Wuqing area, followed by Hanjiang, Qushuikou and Danjiang reservoir areas. Water transparency, chlorophyll-a, dissolved oxygen, TP, pH and DIN have been correlated with rotifer density and biomass, of which SiO₂-Si and dissolved oxygen were significantly contributed to dominant rotifer densities in summer. Dissolved oxygen and pH in autumn, chlorophyll-a, dissolved oxygen and DIN in winter, DIN in spring were significantly contributed to dominant rotifer densities.