随着我国城市进入高质量发展阶段，城市宜居性成为青年流动人口定居考虑的重要因素。基于中国流动人口动态监测数据，结合261个城市的宜居性指标，通过多层logistic回归模型分析城市宜居性对不同家庭生命周期阶段青年流动人口定居意愿的影响及其差异。研究发现，家庭生命周期演进可以塑造青年流动人口的定居决策，从其单身期关注成本与环境的“生存逻辑”到家庭形成期聚焦住房与资产的“筑巢逻辑”，进而向家庭扩张期依赖公共服务与交通的“抚育逻辑”演进。此外，城市规模也起到关键的调节作用。中等城市虽然生活压力小，但基础教育资源短缺，易于陷入“公共服务陷阱”。大城市大量资源配置存在边际效用递减效应，高效率设施建设与运营成为打破拥挤成本的关键。青年发展型城市建设需要建立阶梯式住房支持体系，实施差异化的公共服务补强战略，打造全方位的宜居生态，促进青年定居，进而实现城市的可持续发展。

As China's urbanization enters a stage of high-quality development， urban livability has become a crucial factor influencing the settlement decisions of young migrants. Based on the China Migrants Dynamic Survey （CMDS） data and macro-livability indicators of 261 cities， this study employs a Multi-Level Logistic Regression Model to systematically analyze the heterogeneous impact of urban livability on the settlement intentions of young migrants across different family life cycle stages. The findings reveal that the evolution of the family life cycle profoundly shapes young migrants' settlement decisions， exhibiting a distinct logic of hierarchical transition. Specifically， it shifts from a "survival logic" during singlehood， which highly prioritizes living costs and environmental quality， to a "nesting logic" in the family formation stage， which focuses on housing property rights and asset accumulation， and ultimately evolves into a "parenting logic" in the family expansion stage， which relies heavily on high-quality public services and transport accessibility. Furthermore， city size plays a significant moderating role. Although medium-sized cities offer lower living pressure， they suffer from a shortage of basic educational resources， making them susceptible to the "public service trap". Conversely， large cities exhibit a significant trend of diminishing marginal utility in public resource allocation， where enhancing spatiotemporal service efficiency is key to overcoming the constraints of congestion costs. Therefore， the construction of youth development-oriented cities should avoid homogenized strategies. By establishing a tiered housing support system， implementing differentiated public service reinforcement strategies， and creating a comprehensive livable ecosystem， cities can achieve a win-win outcome for both the permanent settlement of young populations and sustainable urban development.