中文摘要：

根据OLG的养老金均衡模型,人口参数与制度参数（老年支助比、养老金替代率、缴费率等）是决定现收现付养老金均衡的主要参数。PIIGS五国少子老龄化危机及过度慷慨的养老金政策造成养老金长期收支失衡和负债率不断上升。这对各国公共债务危机的成因提供了另一种解释,倘若不能有效解决,还将进一步加重债务危机。为化解公共债务危机,希腊、意大利、葡萄牙等国对养老金制度进行了一系列相关改革：其一是参量改革,主要包括提高退休年龄、削减养老金指数、调整并控制费率等;其二是结构改革,主要是完善多支柱模式并逐步提高职业年金的比重。PIIGS五国的经验和教训对于同样面临人口老龄化困境的中国来说,具有十分重要的借鉴价值。

英文摘要：

According to the overlapping-generations equilibrium model based on pension system,some population parameters and system parameters,such as old-age support ration,replacement rate and contribution rate are key determinants of fiscal equilibrium of pension system. Combining with generosity polity,the population ageing with lower fertility has caused the imbalance of pension payments and the increase of pension liabilities in PIIGS countries. It provides another explanation for the outbreak of the public debt crisis. If not effectively resolved,it would further deepen the debt crisis. Correspondingly,the government has carried out a series of related reforms to pension system in Greece,Italy,Portugal and other countries. One is the parametric reforms that mainly include increasing statutory retirement age,reducing pension index,adjusting contribution rate,etc. The second is the architecture reforms that mainly include establishing the multi-pillars pension system and gradually increasing the proportion of occupational pension. The experience and lessons of these countries have a very important reference value to China,which is also facing the crisis of population aging with lower fertility.