This article conducts in-depth research and analysis on water pollution and treatment in Nanshan Port,Sanya City.With the operation of Nanshan Port for many years and multiple pollutions,the water area of the port is facing increasingly serious water pollution problems.By conducting field investigations and water quality monitoring,the sources of pollutants are analyzed.The MIKE21 mathematical model is used to predict and analyze the diffusion of pollutants in seven different treatment schemes.Taking into account factors such as hydrodynamic conditions,pollutant treatment effectiveness,and economic viability,a comprehensive comparison is conducted from multiple aspects to select the relatively optimal marine water environment treatment plan.The research results can provide reference and guidance for water pollution control in port areas of similar regions.