Urbanization, and the resulting land use/cover change, is a primary cause of the degradation of coastal wetland ecosystems. Reclamation projects are seen as a way to strike a balance between socioeconomic development and maintenance of coastal ecosystems. Our aim was to understand the ecological changes to Jiangsu’s coastal wetland resulting from land use change since 1977 by using remote sensing and spatial analyses. The results indicate that: (1) The area of artificial land use expanded while natural land use was reduced, which emphasized an increase in production-orientated land uses at the expense of ecologically important wetlands; (2) It took 34 years for landscape ecological security and 39 years for ecosystem services to regain equilibrium. The coastal reclamation area would recover ecological equilibrium only after a minimum of 30 years; (3) The total ecosystem service value decreased significantly from $2.98 billion per year to $2.31 billion per year from 1977 to 2014. Food production was the only one ecosystem service function that consistently increased, mainly because of government policy; (4) The relationship between landscape ecological security and ecosystem services is complicated, mainly because of the scale effect of landscape ecology. Spatial analysis of changing gravity centers showed that landscape ecological security and ecosystem service quality became better in the north than the south over the study period.