In order to explore the spatiotemporal variation and driving factors of phytoplankton primary productivity in eutrophic lakes in the middle and lower reaches of Yangtze River, field work and bottling experiments were conducted in April 2020 (spring), August 2020 (summer), October 2020 (autumn) and January 2021 (winter) in Lake Changhu, Hubei Province, while VGPM model was used to estimate the phytoplankton primary productivity (PP_eu). The main environmental factors driving the seasonal change of phytoplankton primary productivity were also explored. According to the results, 194 species of phytoplankton were identified and phyla Chlorophyta (95 species, 49%) and Bacillariophyta (40 species, 21%) were dominant. The total productivity (P_t) value of water column changed as follows:summer ((1841.24±345.93) mg C/(m²·d)) > autumn ((1324.14±208.34) mg C/(m²·d)) > spring ((847.50±247.72) mg C/(m²·d)) >winter ((711.43±133.52) mg C/(m²·d)). The highest value of which was (2424.66 mg C/(m²·d)) at site M2 in summer, while the value of total productivity (GPP) and net productivity (NPP) of phytoplankton gradually decreased with the increase of water depth. The seasonal distribution of PP_eu estimated by VGPM model was autumn ((3713.18±900.30) mg C/(m²·d))>summer ((2643.62±1062.48) mg C/(m²·d))>spring ((2477.13±669.75) mg C/(m²·d))>winter ((708.07±390.4) mg C/(m²·d)), and the trend characteristics of spatial distribution showed Haizihu district>Mahongtai district>Yuanxinhu district. The Spearman correlation between primary productivity measured by bottling experiments and VGPM model (P_t and PP_eu) was significant with a coefficient of 88.2%. They both were highly correlated with phytoplankton density and chlorophyll-a (Chl.a). Multiple stepwise regression analysis showed that PP_eu was mainly influenced by Chl.a, water temperature (WT), pH, total suspended solid and nitrite while Pt can be predicted by conductivity, WT and dissolved oxygen. These data would lay a foundation for the assessment of lake eutrophication and fishery production potential in the middle and lower reaches of the Yangtze River.