Under the dual-driven context of China’s national ecological civilization construction and the Yangtze River Delta integration development strategy, this study investigates the paradigm of Park City development at the county level, guided by Park City theory, using Kunshan, a representative Jiangnan watertown city and one of China’s first “National Ecological Garden Cities”, as an empirical case. Adopting a three-dimensional framework of “theoretical framework - practical pathways - benefit assessment” and leveraging an ecological network analysis perspective, this research systematically analyzes the implementation mechanisms of Kunshan’s four core strategies: blue-green network weaving, park-city integration, contextual placemaking, and innovative governance. The findings reveal three fundamental contradictions in Jiangnan watertown cities: tensions between ecological conservation and urban development demands, conflicts between cultural heritage preservation and spatial modernization, and imbalances between limited county-level resources and comprehensive spatial coordination objectives. Kunshan has established a citywide ecological framework to address these challenges by constructing a “seven-horizontal and four-vertical” ecological corridor system (189 km completed) and a greenway network (489 km). It has advanced park-city integration by developing 446 park green spaces and 410 “Kunxiaowei” micro-regeneration projects (e. g., pocket parks and community gardens), achieving 100% recycling of green waste. The pioneering “City Stewardship” collaborative governance model has also elevated public satisfaction in pilot zones to 93. 27%. This study demonstrates a synergistic development pathway coupling ecological network optimization, spatial quality enhancement, and governance innovation, forming a Jiangnan watertown specific city model characterized by ecological foundation, cultural continuity, and digital empowerment. The Kunshan practice provides theoretical and practical references for county-level Park City development in the Yangtze River Delta and innovatively expands the application boundaries of Park City theory at the county scale. It offers critical insights for coordinating urban-rural ecological governance under China’s new urbanization strategy, establishing a replicable benchmark for balancing ecological integrity, cultural vitality, and sustainable growth in rapidly urbanizing regions.