Abstract: Xiangshan Harbor is the most important breeding harbor in Ningbo City.Cage culture brings rich economic benefits,but also produces a large number of breeding pollutants.Taking a new Larimichthys crocea cage culture base in Xiangshan Harbor as an example,this paper used Delft3D two-dimensional convection diffusion model to predict the impact of pollutants in the culture wastewater on the sea water quality.The results showed that the concentration increment of the three pollutants produced by the new L.crocea cage culture was all higher in the cage culture point,and the pollutants outside the cage moved rapidly with the tide,while the concentration increment decreased.Due to the small scale and short time,the impact of the pollutants on the water quality of Xiangshan Harbor was not significant.However,as the active phosphate and inorganic nitrogen in Xiangshan Harbor have exceeded the standard,it is still necessary to strictly evaluate the pollutant emission concentration of the newly added cage culture,effectively protect the marine environment of Xiangshan Harbor,and promote the sustainable development of the aquaculture industry in the sea area.This paper provided a reference for the prediction of the newly added cage culture pollutants.