This project aims to strengthen and implement the reduction of nutrient pollution and improve water quality in the catchment area, to ensure clean water resources, and to improve the water quality of major reservoirs and water bodies by planning a water quality improvement strategy, proposing measures to reduce pollution, and implementing a model reduction test for the outlying island area. (1) This project develops appropriate pollution reduction and water quality improvement strategies for the outlying islands area, and propose a three-pronged improvement strategy from upstream, midstream, and downstream for reference by the administration and management units. (2) The results of the surface water survey indicate that there is a possibility of sewage leakage or overflow in the catchment of the outlying islands reservoir, which has a certain degree of impact on the water quality of the reservoir and needs to be further controlled. (3) The 3-month test results of Taihu MSL pilot plant in Kinmen show that the flow from the MSL plant can generally meet the treatment target, but further testing is still needed, and enhance the effectiveness of the pre-treatment treatment. The 4-month test results of the MSL system in Lienchiang showed that there was an excessive amount of aeration set at the site, so the setting of the aeration timing needs to be revised again. In addition, in the planning of the on-site MSL in Kinmen, it is suggested that in the future, ecological conservation, environmental education and tourism can be combined with other related issues to improve the effectiveness of the on-site MSL installation.