Abstract: In order to study the water quality of the shellfish culturing areas in the Dongying River estuary, Shandong Province, seasonal monitoring of seawater quality was carried out from 2020 to 2021.The study used the Nemerow environmental composite quality index (P), the trophic state index (E) and the organic pollution assessment index (A) to evaluate the quality of the water environment.The results of the study showed that, with the exception of a few monitoring points in the autumn mudflat area, the physicochemical indicators and nutrient salts of the seawater in the Dongying estuary shellfish culturing area all met the seawater quality standard of Class Ⅱ, indicating that the seawater quality in the Dongying River estuary shellfish culturing areas was good.However, there was a trend towards eutrophication in local areas of the tidal flat breeding area in the autumn.Meanwhile, it should be paid attention to the variation of chemical oxygen demand (COD) and inorganic nitrogen (DIN) in autumn.The results of this study could provide a scientific basis for the ecological management of the water environment in the shellfish culturing areas.