In order to better understand the status of phytoplankton resources in Xinzhou waters in Anqing, four sampling surveys were conducted in February, April, August and November, 2017. The results showed that 143 species of phytoplankton belonging to 8 phyla were detected in this study, of which Chlorophyta was the most, accounting for 46.15%; Secondly Bacillariophyta, accounting for 29.37%; Cyanophyta, Euglenophyta, Chrysophyta, Cryptophyta, Pyrrophyta and Xanthophyce aeaccounted for 12.59%, 3.50%, 3.50%, 2.10%, 1.40% and 1.40% respectively. There are 6 dominant species of phytoplankton, including Pseudoanabaena sp. of Cyanophyta, Synedra acus and Cyclotella meneghiniana of Bacillariophyta, Chroomonas acuta and Cryptomonas erosa of Cryptophyta, Ulothrix sp.of Chlorophyta. The density of phytoplankton ranged from 14.09×10⁴ to 487.98×10⁴ cell/L, with an average of 63.05×10⁴ cell/L. The biomass change was between 0.07 and 1.41 mg/L, with an average of 0.28 mg/L. The highest density occurs in Huangpen Zha rivers in summer(Section 5), the lowest density occurs in Xinzhouwei waters in spring (Section 7), the highest biomass occurs in Dongjiayao rivers in summer (Section 6), and the lowest density occurs in Wanhe estuary in summer (Section 1). The Shannon-Weiner index (H') ranged from 1.93 to 3.10, with an average of 2.70, the Margalef richness index (D) ranged from 1.12 to 3.00, with an average of 2.21, and the Pielou evenness index (J) ranged from 0.52 to 0.93, with an average of 0.79. Shannon-Weiner index (H'), Margalef richness index (D) and Pielou evenness index (J) had significant differences in spatial distribution, but no significant differences in seasonal variation. The index of diversity evaluated water quality as light to medium pollution, indicating that the water quality of Xinzhou waters was in good condition.