In the process of 30 years’ reform and opening up of China，a basic framework of social security system has been gradually established，the process of which can be divided into four stages. Today，the social security system still faces many problems：while a multi-pillars approach has been adopted，there lacks organic connection between each pillar；the combination model of social pooling with individual accounts （IAs） is intended to reap the merits of the two elements，that is，income redistribution of the social pooling for social solidarity and funding of IAs for sustainability of the system，however the IAs have not been funded due to unresolved transition cost；while the coverage has expanded，the system is fragmented into several part for different groups. In the process of social security reform，two important issues should be noticed. First，government should strike a balance between economic policy and social welfare policy. Second，government should deal with the relationship between the combination model and partially funded system. In short，reform and development of Chinese social security system shall be guided by the Scientific Outlook on Development.