With the increasing trend of China's aging population,the balance of endowment insurance found payments will face enormous pressure in the future and the government sector will implement a deferred retirement policy.A reasonable expenditure level model of China's social endowment insurance fund was proposed according to the theory of population structure and Cobb Douglas production function.Through the establishment of China's residents endowment expenditure forecast model and GDP forecast model,the actual expenditure level prediction model for the China's social pension insurance fund was provided.Following the point of view that the actual payment level of the endowment insurance fund should be close to its reasonable payment level,the core issue in what year the deferred retirement policy would begin to implement was solved.Through the analysis and verification,some suggestions were put forward on the related problems of the deferred retirement policy.