Abstract: In recent years, the ecological environment of the mangrove wetland in Dongzhai harbor, Hainan has been seriously polluted.In addition, the marine Sphaeroma had erupted in the protected area in 2012, causing serious damage to the mangroves.Therefore, it is necessary to conduct pollution monitoring, pollution source analysis, ecosystem health diagnosis, assessment and early warning of mangrove wetland in Dongzhai harbor, Hainan.On the basis of monitoring and ecological investigation of the mangrove wetland in Dongzhai harbor for five consecutive years, this paper used single factor pollution index, Nemero index and comprehensive trophic level index to evaluate the pollution and change characteristics of the mangrove area in Dongzhai harbor and explore the causes of major pollutants.The corresponding countermeasures and suggestions were put forward for the recovery of the system.The results showed that the pollution of mangrove wetland in Dongzhai harbor, Hainan had experienced a gradual reduction from 2013 to 2015, and a further serious pollution from 2016 to 2017.According to the three methods of pollution assessment, the most serious pollution and eutrophication places were Tashi, Shanwei village and Sanjiang town in recent two years, and the main water pollution was organic matter and nitrogen pollution.Relevant management departments should strengthen supervision and take appropriate measures to control the number of high-level pond shrimp culture, implement measures such as returning ponds to forests and shrimp pond culture wastewater treatment, so as to restore the mangrove ecosystem in Dongzhai harbor, Hainan.