To gain a better understanding the inference of the Water and Sediment Discharge Regulation (WSDR) project on the marine biodiversity in the estuary and adjacent area, we investigated surveys at 8 stations in June and July. In each station, the abundance and/or biomass of every species, including Phytoplankton, Zooplankton, Macrobenthos, Ichthyoplankton and Nekton were recorded. The numbers of species (S), abundance (N) and/or biomass (W), Margalef richness index (D), Shannon-Wiener diversity index (H') and Pielou's evenness index (J') were calculated. A t-test was used for testing if there exists significant difference between the two surveys. The result showed that even the values of S, N or W, D', H' and J' changed after WSDR, but no significant difference were found in each index of Zooplankton, Ichthyoplankton and Macrobenthos. Some indexes, such as S, D and J' of Phytoplankton, W of Nekton, has significant difference between the two surveys.