Lake Wuliangsuhai is a very important part of irrigation and drainage system of Hetao irrigation area. It is also an important migration and breeding ground for Northern China migratory birds. The wetland was listed in in 2002. The present investigation deals with the aquatic status of Lake Wuliangsuhai from April 2004 to January 2005. The study revealed that there were 62 species of zooplankton belong to 34 genera in the lake, which include 16 species of Protozoa belong to 11 genera, 33 species of Rotifera belong to 17 genera, 4 species of Cladocera belong to 4 genera, and 9 species of Copepodo belong to 5 genera. The average abundance and biomass of macrozooplankton were 687ind./L and 3.4985mg/L and Protozoa were 2.508×10⁴ind./L and 0.1254mg/L, respectively. There were 11 species of zoobenthos found in the lake, which belong to 4 families. The average abundance and biomass of zoobenthos were 3031.4ind./m²and 71.67g/m². The abundance and biomass of zooplankton changed significantly with seasons. The abundance and biomass in the Spring and Summer are dramatically higher than in Autumn and Winter. The biomass of zooplankton and zoobenthos were used as indicators of water body status to evaluate the nutritional status and the results showed that the lake was in the status of eutrophication.