In order to improve water quality management for urban water sources and their adjacent waters, sample were collected in Zhongyangsha Reservoir and Lake Nanbaidang in four seasons from November 2019 to November 2020. The comprehensive trophic level index (TLI(Σ)) was used to assess the trophic state levels of water bodies, and the relationship between the characteristics of phytoplankton communities and environmental factors were studied using principal component analysis (PCA), redundancy analysis (RDA) and correlation analysis. It is shown that theTLI(Σ) ranged over 57.5-59.0 and 54.1-56.1 for Zhongyangsha Reservoir and Lake Nanbaidang, respectively, and both water bodies were in a mildly eutrophic state. The phytoplankton species were identified with 184 species of 7 phyla and 104 genera, and 172 species of 8 phyla and 96 genera in Zhongyangsha Reservoir and Lake Nanbaidang, respectively. Cyanophyta was the major group throughout the year in the Zhongyangsha Reservoir, followed by Bacillariophyta and Chlorophyta, while the seasonal succession of the phytoplankton community structure in Lake Nanbaidang changed mainly from Bacillariophyta/Cryptophyta-Cyanophyta-Cryptophyta/Bacillariophyta. The seasonal mean density of phytoplankton was 30.0 million-161 million cells/L and 4.29 million-65.9 million cells/L. The dominant species of phytoplankton in the Zhongyangsha Reservoir and Lake Nanbaidang were identified as 4 phyla and 17 genera, and 5 phyla and 13 genera, respectively. The main dominant species in Zhongyangsha Reservoir were Pseudanabaena and Dolichospermum throughout the year, while in Lake Nanbaidang the main dominant species were Cyclotella, Cryptomonas and Chroomonas in spring and winter, and Pseudanabaena, Merismopedia and Microcystis in summer and autumn. The results also indicated that the changes in the structure of the phytoplankton community in Zhongyangsha Reservoir were mainly related to environmental factors such as total nitrogen, total phosphorus, and water temperature, while in Lake Nanbaidang changes were mainly related to water temperature, total dissolved solids etc., and the differences in water circulation played a key role.