摘要： 年龄中位数是衡量人口老龄化程度的重要参量，其上升不仅带来社保支出增长的经济效应，还会通过人口结构变化引致改革的政治约束。通过对 OECD 国家年龄中位数效应的比较分析可以发现，老年福利偏好、高投票率以及预算赤字转嫁，构成银发政治制约养老金制度改革的传导机制。对德国、希腊和日本三个案例国家进一步剖析可以发现，不同制度环境下改革路径呈现显著差异：成功的改革不仅依赖于理性政府的顶层设计，更依赖于社会团结的建立与渐进过渡策略的运用。在人口老龄化加速的背景下，中国同样面临年龄中位数上升带来的双重压力，养老金制度改革应把握窗口期，通过降低第一支柱福利依赖，强化立法规则，优化政策选项，实行渐进过渡，增进社会共识。

关键词: 年龄中位数, 银发政治, 养老金制度改革, OECD 国家, 人口老龄化

Abstract: Median age is an important parameter for measuring the degree of population ageing. Its increase not only generates the economic effect of raising social security expenditure, but also imposes political constraints on reform through demographic shifts. A comparative analysis of the median-age phenomenon in OECD countries reveals that elderly welfare preferences, high voting rates among older groups, and the intergenerational shifting of budget deficits constitute the transmission mechanisms through which silver politics constrains pension system reform. Further examination of Germany, Greece, and Japan reveals significant differences in reform trajectories across varying institutional contexts. Successful reforms depend not only on rational top-level design by the government, but also on fostering social solidarity and adopting gradualist strategies. Against the backdrop of accelerating population ageing, China likewise faces the dual pressures brought by a rising median age. Pension system reform should seize the window of opportunity by reducing reliance on first-pillar benefits, strengthening legislative rules, and pursuing a gradual reform path, thereby building social consensus and achieving sustainable development.

Key words: median age, silver politics, pension system reform, OECD countries, population ageing