以“瘦身健体”改革为准自然实验，基于2011～2019年A股上市公司样本，研究发现，改革显著提升了国有企业劳动投资效率，主要通过改善管理层治理效能与优化人力资本结构两条路径实现。异质性分析表明，改革效果受内外部制度环境调节，在法律制度完善、劳动力市场发育良好、高管晋升预期明确以及外部监督较强的企业中更为显著。进一步研究发现，改革效应呈现结构性差异，即在有效缓解劳动投资过度的同时，对劳动投资不足的改善作用有限，且后者仅在内部激励充分、能力基础扎实的企业中有所显现，反映出改革在“去冗余”与“补不足”之间的非对称性。

Taking Chinese “Lean-and-Healthy” Reform as a quasi-natural experiment and based on the sample of A-share listed firms from 2011 to 2019, this study finds that the reform significantly improves the labor investment efficiency in state-owned enterprises. The effect operates primarily through enhanced managerial governance effectiveness and optimized human capital structure. Heterogeneity analyses show that the effect of the reform is highly dependent on internal and external institutional environments, with more pronounced effects in firms with well-developed legal systems, mature labor markets, clear executive promotion expectations, and strong external supervision. Further research reveals a structural difference in the reform effects: while the reform effectively mitigates overinvestment in labor, its impact on alleviating labor underinvestment is limited and emerges only in firms with strong internal incentives and solid capability foundations, which highlights the asymmetric role of the reform in “reducing redundancy” versus “making up for deficiencies”.