The study was carried out to assess surface water quality in water bodies in Hau Giang province, Vietnam using individual surface water quality parameters and water quality index. In addition, the correlation of phytoplankton and zooplankton composition with surface water quality was also examined. The results showed that surface water quality in Hau Giang province was contaminated with organic matters, nutrients, iron and microorganisms. The water quality index (WQI= 37-84) showed that surface water ranged from moderate to good. A total of 164 species belonging to five phyla of phytoplankton were recorded with the density from 370-2260 individuals/L and 91 species belonging to five phyla of zooplankton with a density of 11,332- 121,600 individuals/L. The predominance of the phytoplankton species Oscillaroria, Euglena, Phacus and the predominance of zooplankton species of the Nauplius, Rotifera and Protozoa signalize an aquatic environment rich in organic matters and nutrients. The correlation results showed that BOD, COD, NH4+-N, NO3--N and PO43--P were closely related to the density of phytoplankton while pH, DO, BOD, NH4+-N and coliform play an important role in determining the density of zooplankton species.