Abstract: The 22 sample sites of Qingshui river basin were surveyed in July （summer） and November （winter） 2018,the zooplankton species composition, density, biomass, common species,dominant species composition and seasonal variation were studied to explore the population structure and diversity of zooplankton in Qingshui river basin. The results showed that 23 species of zooplankton were identified in Qingshui river basin, including 8 species of rotavirus, 8 species of dendritic and 7 species of copepods. There were 6 kinds of dominant species, of which the daphnia was the most sharp. Zooplankton species, density, biomass and distribution varied by season, with summer species, densities and biomass peaking and winter at a low ebb. The Margalef index of zooplankton in Qingshui river basin was 0.432~0.997, Shannon-Wieaver index was 1.251~1.922, and evenness index was 0.233~2.066. The structure and diversity of zooplankton population were different in different sampling sites. According to Margalef index, Shannon-Wieaver index and evenness index, it can be preliminarily judged that water quality in Qingshui river basin is seriously polluted and moderately eutrophic, which needs to be strengthened for treatment and protection.

Key words: species composition, density, biomass, seasonal variation, diversity index