Despite the fact that a preliminary retirement pension system covering different groups of people has been established during the last decade in China, it features stratification due to the political pushing approach varying with each individual. The pension system in China hasn't bridged the income gap; on the contrary, the divided pension system has enlarged people's income gap in the market. The evolution approach of China's pension system implies the political appeal of national governance. Political design logic of early period has generated certain lock-in effect for the evolution approach of pension system for the following decade, which has led to the decline of allocation function and become the system root of the further increasing income gap. In spite of the continuous enlargement of pension system and its coverage during recent years, the contribution to social justice is still limited with reverse redistribution of system, which reflects the involution of China's welfare system.