Abstract: Analyzing LUCC (Land Use and Cover Change) is of great significance for improving land development and utilization efficiency and promoting ecological environment protection work. This article selects the Sanmen Bay coastal zone as the research area, and uses Landsat images from six periods from 1987 to 2020 as the data source. GIS and RS technologies are used to analyze the spatial and temporal patterns of land use in the Sanmen Bay coastal zone using quantitative analysis and land transfer matrix models. The results show that: ① Construction land, cultivated land and aquaculture land are the dominant land use types in the coastal zone of Sanmen Bay. Human activities and urbanization have led to the increase of construction land and aquaculture area. The transfer of land use is mainly manifested in the trend of farmland to construction land, and mudflat to aquaculture land. ② Under the influence of changes in land use structure and properties, the nutrient content in the nearshore water of Sanmen Bay has shown a trend of first increasing and then decreasing in the past 30 years; In the past 20 years, the coastal comprehensive potential ecological index has increased from 16.47 to 21.18; Human activities threaten the coastal ecological environment of Sanmen Bay.