What is the relationship with environmental factors of phytoplankton community dynamics in saline lakes? We analyzed a data set of phytoplankton community and environmental parameters in seasonal periods (i.e., summer and autumn) in order to describe seasonal variations within the phytoplankton community and its relationship with environmental variables in Chagan Nur Lake on the Ordos Plateau in China. The lake’s phytoplankton species was not abundant, with a mean density of 222.43×10⁴ cells/L (ranging from 62.35×10⁴ cells/L in autumn to 382.5×10⁴ cells/L in summer 2014). However, the groups with highest densities were essentially limited to Bacillariophyta, Chlorophyta, and Cyanophyta. There were considerable seasonal variations in phytoplankton composition. Eleven environmental variables were selected to explore the relationship between phytoplankton structure and environmental factors by canonical correspondence analysis (CCA). The results of the CCA applied to the environmental factors indicated that total phosphorus (TP), pH, total ion degrees (Tds), salinity (Sal), and electrical conductivity (Con) significantly influenced the phytoplankton community (p<0.01; Monte Carlo test of first constrained axis).