主体功能区是国土空间开发保护的基础制度，核心目标是以差异化的功能定位，引导要素有序流动，优化国土空间发展格局。本文基于2000年、2010年和2020年3次全国人口普查分县数据和双重差分模型，评估主体功能区规划对人口分布变动的影响。研究发现：① 主体功能区规划对人口变动的影响总体符合政策导向。规划实施后，人口在优化开发区的增速下降，重点开发区加速增长，农产品主产区加速减少，重点生态功能区由增转减；以农产品主产区为参照，规划的实施强化了重点开发区的人口集聚优势。② 规划实施效果具有区域和等级双重异质性。农产品主产区和重点生态功能区的县域人口变动多半符合规划导向，而重点开发区的县级单元仅四成实现了人口加速集聚的目标；国家级重点开发区的影响强度约为省级的2倍。③ 限制开发区向城市化地区的迁移仍以跨区域为主，很难实现人口“集中均衡”布局的目标。④ 规划的实施改变了各类主体功能区人口变动的影响因素。优化开发区的二产重要性弱化、三产带动力增强，重点生态功能区的经济因素弱化，都符合规划导向；但重点开发区的工业化作用有限，农产品主产区则持续受到工业化和经济发展的深刻影响，二者与规划导向均有明显偏差。新一轮规划可适度集中城市化地区的布局，明确重点开发区的开发时序，对各类限制开发区提出更具针对性的管控要求。

Main function zoning (MFZ) is the fundamental system of China's territorial development and protection. Through differentiated functional orientation, the core objectives of MFZ are to guide the orderly flow of resources across regions and optimize the spatial pattern of national development. This study evaluates the impacts, their heterogeneities among four types of zones, and underlying mechanisms of MFZ planning on China's population redistribution using county-level data from the three latest national population censuses and causal inference tests through difference-in-differences models. The results show that: The MFZ effects generally align with policy orientation. Post-implementation, optimized development zones, prioritized development zones, main agricultural zones and key ecological zones experienced declining population growth rates, accelerated population agglomeration, accelerated population decline, and growth-to-decline transition, respectively. Using main agricultural zones as reference, the planning reinforced the population concentration advantages of prioritized development zones. The policy effect exhibits dual heterogeneity across regions and hierarchical levels. Population changes in agricultural and ecological zones mostly complied with planning guidance, whereas only 40% of county-level units within prioritized development zones achieved the policy goal of accelerated agglomeration. National-level prioritized development zones demonstrated approximately twice the impact of provincial-level counterparts. Population migration from restricted development zones to urbanized areas predominantly occurred through cross-regional migration rather than intra-prefecture movements, making the policy goal of "concentrated equilibrium" within prefecture-level cities difficult to achieve. The planning promoted shifts in influencing factors of population redistribution within each type of MFZ. The diminished role of secondary industries and enhanced influence of tertiary sectors in optimized zones, along with weakened economic drivers in ecological zones, aligned with planning objectives. However, industrialization in prioritized development zones failed to significantly boost population agglomeration, while agricultural zones remained profoundly influenced by industrialization and economic development, both deviating from intended planning orientations. The findings suggest that the new-round planning could moderately concentrate urbanized area layouts, clarify development sequences for prioritized development zones, and implement more targeted differentiated governance requirements for restricted development zones.