This paper develops life-cycle models for the main social security systems: the state-securedsystem, the welfare state system, the compulsory savings system and the social insurancesystem. All four life cycles are similarly composed of birth, growing, peak, decline and deathstages. China is in the growth stage of the social insurance model and is expected to enter thepeak in 30 years or so, by a series of proposed efforts in economic reform and policies. This paper develops life-cycle models for the main social security systems: the state-securedsystem, the welfare state system, the compulsory savings system and the social insurancesystem. All four life cycles are similarly composed of birth, growing, peak, decline and deathstages China is in the growth stage of the social insurance model and is expected to enter thepeak in 30 years or so, by a series of proposed efforts in economic reform and policies.