Abstract: Four different total dissolved solids (TDS) gradients (0.5,1.5,3.5and 10.0g/L) were set up to investigate the effects of various TDS on the dynamics of phytoplankton population and their growth. The primary constitutes of salt added to the culture solution were SO₄^2- and Cl^-, which accounted for 36.60% and 22.03%, respectively. The results demonstrated that during the logarithmic phase, the number of phytoplankton, growth rate, biomass and chlorophyll-a increased as total dissolved solids (TDS) increased. However, phytoplankton growth was restrained by high TDS in the later culture period. Bacillariophyta were the most advancded with more than 95% of the total species in every treatment group. With the increment of TDS, cyanophyta got better adaptability, while the inhibitory effect on Chlorophyta was obvious. Experiments showed that Fragilaria、Synedra、Navicula and Pinnularia were dominant species. Navicula rarely appeared under TDS (0.5g/L). However, it gradually became a dominant species, whose proportion ranged from 18.51%-26.18%. In contrast, Pinnularia accounted for 3.40% and 4.94% respectively at TDS of 0.5and 1.5g/L, then could hardly grew at high TDS (3.5-10.0g/L). The results demonstrated that Navicula and Pinnularia could be used as indicator species to identify the salinizing process of Lake Bosten.