108 species of phytoplankton of Vinh Long province have been identified in 2012. Those species belong to five phylasuch as Cyanophyta. Bacillariophyta, Chlorophyta. Euglenophyta, and Dinophyta. Among them, Bacillariophyta is the dominant phylum. Not only Diatom is diverse on compositon, but their quantity is also high at some of sites. However Cyanophyta is also popular phylum and advantages in quantity at almost of sites. The other phyla is low in species composition and quantity.