<p>As the pursuit of quality life continues to increase and the environmental and health challenges become greater after COVID-19, a large number of older adult amenity migrants (OAM) are relocating to areas with superior environments. This study aims to investigate the relationship between greenspace characteristics and older adult amenity migrants’ subjective well-being (OAMSWB), which can deepen the environmental needs of the elderly in second-home and provide guidance for enhancing their well-being. Using Maodao Town in Lichuan City, an ecological tourism destination in China, as a case study, we integrate greenspace with social survey data to build multilevel ordered logistic models that examine how availability, accessibility, landscape patterns, tranquility, and attractiveness influence OAMSWB. Mediating variables (e.g., frequency of visits and exercise) were integrated into the analysis, to create a multilevel mediator model. The results show that, (1) Greenspace characteristics have positively affected on the OAMSWB, though the strength of each dimension varies. (2) Frequency of visits has a significant mediating effect, tranquility, and attractiveness can enhance the OAMSWB by increasing the frequency of visits, but availability, accessibility and landscape patterns, although increasing the frequency of visits, can cause overcrowding and other problems, which leads to the decline of the OAMSWB. (3) Different dimensions of greenspace features interact complementarily, jointly amplifying their impact on OAMSWB. This study reveals the complex links between greenspace characteristics and OAMSWB, and provides targeted policy recommendations for second-home planners to optimize the layout, improve the quality of greenspace, and propose targeted policies.</p>