This paper studied the diversity of phytoplankton species at 9 sampling points of aquaculture ponds in Dak Ha, Sa Thay and Kon Plong districts, Kon Tum province (now Quang Ngai province) in 2022–2023. The results recorded 7 phyla, 98 genera, and 142 species, of which 22 genera and 23 species of phytoplankton were present in all 3 sampling periods. The values of the biodiversity index (H^’) and the diversity value index (Dv) at 9 sampling points ranged from 2.51–3.66 and 2.39–3.58, indicating that the diversity of phytoplankton in aquaculture ponds is high and very high, respectively. The regulation index (J) ranged from 0.95 to 0.99, indicating that phytoplankton species were evenly distributed at all studied sampling points. The similarity coefficient of species composition of phytoplankton populations at 9 sampling points ranged from 0.43 - 0.85. In water samples collected at 9 study locations, the number of phytoplankton species was negatively correlated with impedance. In particular, at the sampling locations, the main environmental factors such as suspended solids, salinity, and conductivity affecting the cell density of phytoplankton communities had a positive correlation and a negative correlation with impedance.