In order to find out the characteristics of phytoplankton community structure of Zhangfu River, three surveys and samples were conducted in July(summer), September(autumn)and December(winter)of 2019. Niche of the dominant species of phytoplankton was measured by the improved Levins niche width and Petrailis niche overlap index. The results show that a total of 140 species of phytoplankton are identified in the samples taken. The total average density is greater in autumn than in summer and also than in winter. There were 16 dominant species, mainly Diatom and Chlorophyta, and most of which are the mesotrophic and eutrophic indicator species. The seasonal change was significant. The dominance index varies from 0. 021 to 0. 360. The niche width varies from 0.333 to 0.966, The niche overlap index varies from 0.000 to 0.998, The above results indicate that phytoplankton species in Zhangfu River are abundant, but there is a potential risk of water bloom.