Establish mathematical model and actuarial model of income and expenditure of basic endowment insurance to test the impact of national unified income and expenditure on financial sustainability of basic endowment insurance. The research finds that the realization of national unified income and expenditure can improve the financial sustainability of basic endowment insurance; The earlier the national unified income and expenditure is realized, the more the financial sustainability of basic endowment insurance will be improved; For the financial sustainability of basic endowment insurance, it is better to implement the national unified income and expenditure policy and delayed retirement policy at the same time than to implement the national unified income and expenditure policy alone; properly increasing the growth rate of financial subsidies can improve the financial sustainability of basic old-age insurance under unified revenue and expenditure. Therefore, we should improve the national overall planning system of basic endowment insurance; establish a national overall planning system for basic old-age insurance based on national unified income and expenditure; increase pension fund income through multiple channels; establish a gradual delayed retirement system.