Abstract: By integrating remote sensing and field survey data, a Coastal Wetland Ecosystem Health (CWEH) assessment model was constructed, integrating external, internal, and ecological factors, with significant spatial heterogeneity. A key feature of this model is its comprehensive consideration of spatial scale effects on assessment results, aiming to establish a universal, multi-scale, comprehensive assessment framework that accurately reflects the health of coastal wetlands. This study, focusing on the Yancheng coastal wetlands in Jiangsu Province, assessed the ecological health status and its spatiotemporal trends from 1992 to 2020. The results showed that the CWEH results within the study area in 2020 were favorable, with significant spatial heterogeneity. The proportion of areas with different CWEH statuses, in descending order, was as follows: 55.4% for the best, 25.7% for good, 17.1% for fair, 1.8% for poor, and 0% for the worst. The ecological health assessment results for the study area were 0.55, 0.54, 0.52, and 0.50 in 1992, 2000, 2012, and 2020, respectively, showing a continuous downward trend. Significant differences in CWEH were observed between the inside and outside of the nature reserve, with CWEH significantly higher inside than outside. At spatial scales of 100 to 500 m, CWEH for the entire study area gradually decreased with increasing spatial scale; the results at the 100 m scale best demonstrated spatial heterogeneity. Human interference, landscape pattern, and ecosystem productivity were the most significant factors influencing CWEH. From 1992 to 2020, human activities and increased coastal erosion led to a decrease in CWEH, while coastal embankment and nature reserve construction improved CWEH in some areas. As the influence of natural factors continues to weaken, human activities have become the main driving force of the spatial variation of CWEH.