During August 2001 to August-September 2002, an investigation on the characteristics of community diversity of plankton was conducted at some shallow saline lakes in Inner Mongolia, China. Fifty-nine species(genera) of phytoplankton were identified, and the dominant species were Chlorella vulgaris, Dunaliella salinay Eugliena viridis, Gloeothece linearis, Chlamydomonas sp., Dactylococcopsis rhaphidioides, Phorimidium tenuusy Merismopcdio terms and Navicula sp.. Thirty-four species(or genera) of zooplankton were identified, and tlie dominant species were Brachionus plicadlis, Brachionus calyciflorus, Artemia sp., Cyclidium sp., aholophrya sp., Tetrahymena sp., Stylonychia sp., Arctodiaptomus salinus, Arctodiaptomus stewartianus, Moina mongolica. The average annual biomass of phytoplankton was 166.56 mg/L in the Dageer; That was 106.77 mg/L, 6.39 mg/L and 2.83 mg/L in the Zagesitai, Xiari and Sanggendalai, respectively. The average annual biomass of zooplankton was 246.54 mg/L in Sanggen-dalai;That was 27.24 mg/L. 12.01 mg/L and 2.76 mg/L in the Zagesitai, Xiari and Dageer, respectively. The relationships between species composition of plankton, distribution, biomass ^salinity tolerance and salinity, nutrients, alkalinity, pH, ionic composition were discussed.