The construction of the social security system, which matters the stability of a nation, is the essential issue of people's livelihood and one of the most important social and economic systems of the country. The 19th National Congress of the Communist Party of China explicitly proposed to construct a multi-tiered social security system. This paper reviewed the relevance theories and existing literature concerning the construction of the multi-tiered social security system, studied and proposed the basic principles for the construction of China's social security system, on which basis the paper also attempted to propose the key direction for the ways to construct a multi-tiered social security system and overall design as well.