Abstract: As population ageing deepens in China, promoting economic growth has become an urgent issue. Previous studies have mainly examined its impact on economic growth through changes in aggregate savings or rising pension deficits. Although some studies embed savings and pensions in a unified framework, most still view their relationship as merely a substitution mechanism in old-age security, paying insufficient attention to differences in allocation structure and efficiency, as well as their broader implications for long-term economic growth.

Against this background, this paper incorporates the three-pillar pension system into a general equilibrium overlapping-generations model and constructs an indicator of the pension-savings conversion rate. Using numerical simulation, it investigates how savings are transformed into pensions under population ageing, identifies the optimal scheme and parameter combinations, and evaluates the adaptability and relative advantages of different schemes.

The conclusions are as follows. First, population ageing affects economic growth not mainly by changing aggregate savings, but by impeding the effective conversion of savings into pensions and thereby weakening capital formation. Second, the three-pillar coordinated Scheme P4 is the optimal choice for coping with the ageing shock and sustaining long-term economic growth. The results further suggest that the current parameter settings of China's first and second pillars are broadly appropriate, whereas the third pillar still has room for improvement. The theoretically optimal parameters for the third pillar are an annual contribution ceiling of RMB 19336 and a tax rate of 2.31% on pension benefit withdrawals. Third, simulations of future ageing scenarios show that if the system continues to rely heavily on the first pillar, which is dominated by pay-as-you-go (PAYG) financing, China's basic pension insurance system will face an unsustainable contribution burden. As population ageing intensifies, a transition from PAYG financing toward funded pillars is therefore necessary.

Based on these findings, future reforms should accelerate the development of the second and third pillars while maintaining the basic protection function of the first pillar. Priority should be given to improving contribution incentives, tax preferences, and account portability mechanisms for the third pillar, and to broadening the conversion of savings into pension capital through pension financial product innovation, thereby strengthening the supply of long-term capital. The pension system should also be better coordinated with medical insurance and long-term care insurance to reduce precautionary savings driven by health and care risks.

The marginal contributions of this study are twofold. First, it extends the existing framework, which has largely focused on the first-pillar basic pension system, by incorporating the three-pillar pension system into a general equilibrium overlapping-generations model and constructing an indicator of the pension savings conversion rate. This enables the paper to examine the mechanism through which population ageing affects economic growth from the perspective of savings structure optimization. Second, this paper moves beyond the social security function of the pension system and reconceptualizes it as an instrument for improving the pension savings conversion rate, thereby identifying the reform scheme and parameter combinations that maximize the growth-enhancing effect of savings conversion.

Keywords: Population Ageing, Savings Structure Optimization, Economic Growth

摘要： 在中国人口老龄化程度持续加深的进程中，如何推动经济增长，成为亟待解决的问题。本文将三支柱养老金体系纳入一般均衡世代交叠模型，构建养老金储蓄转化率指标，从储蓄向养老金转化的视角分析老龄化影响经济增长的作用机制，并结合数值模拟和反事实分析识别促进储蓄向养老金转化的最优方案及参数组合。研究发现，老龄化通过抑制储蓄向养老金转化，削弱资本形成效率，进而制约经济增长。方案比较显示，三支柱协同方案具有更优的经济增长效应。参数识别结果表明，现行第一、第二支柱的参数已基本合理，第三支柱在缴费激励和税制设计方面仍有优化空间。情景模拟显示，随着老龄化程度加深，若继续高度依赖现收现付制，将显著加大基本养老保险体系的缴费压力。因此，建议完善三支柱养老金体系，尤其应加快发展积累型支柱，并可通过创新养老金融工具促进储蓄向养老金转化。

关键词: 人口老龄化, 储蓄结构优化, 经济增长