To understand the status of phytoplankton community of the Genhe River in the summer of 2015, we investigated the phytoplankton in Genhe River. We identified 5 phyla and 36 species, among which Bacillariophyta (23) were the most, followed by Chlorophyta (10), Cyanophyta (1), Chrysophyta (1), Pyrrophyta (1). The phytoplankton abundance was (15.6-810)×104 ind·L－1; the biomass was (0.07-2.876) mg·L－1; Shannon-wiener index was 1.05-3.24; Pielou evenness index was 0.27-0.96. Using Shannon-wiener index and Pielou index, the water quality of Genhe River was assessed, and the results showed that the water quality was the best at 5# sampling point, the water quality was good in 3#, 4#, 7#, 8#, 9# sampling points, and there was a state of pollution at other sampling points. Canonical correspondence analysis and Pearson correlation analysis showed that iron ion, transparency, pH value, water depth and water temperature were important environmental factors that affect the distribution of phytoplankton, and copper ion, nitrite ion and COD also significantly affected the distribution of phytoplankton.