This paper introduces the population structure, the fiscal expenditure structure and the monetary policy into the new Keynesian dynamic stochastic general equilibrium framework, focusing on the analysis of the impact of population aging on China’s macro-economic control policies. The results of the study show that: In addition to the negative impact of the aging population itself on economic growth, the space for maneuvers left for macro-control policies has become increasingly limited, affecting the effectiveness of policy control and increasing the cost of policy implementation.　　First, with the aging population structure, the positive effects of macroeconomic control policies have been weakened and the negative effects have been strengthened. This shows that population aging has undoubtedly weakened the effectiveness of fiscal and monetary policies. In terms of macroeconomics, the basic effect of population aging is that it will profoundly change the relationship between the national income distribution pattern and the allocation of economic resources. In the long run, population aging reduces labor supply, and the overall economic life cycle gap widens the lack of economic growth and the overall welfare level of society continues to decline. In the short term, accelerating the burden of financial pensions has significantly reduced the space for fiscal policy maneuvers and also weakened the ability of the government to implement anti-cyclical fiscal policies. In terms of policy assessment, the decline in fiscal multipliers has masked the enthusiasm of the financial sector, amplifying its crowding-out effect and impairing the quality of financial performance. In terms of the monetary policy, population aging may bring deflationary pressures, limit the monetary policy’s ability to stimulate aggregate demands, force the Central Bank to adopt more radical measures to achieve the same effect, and be directly exposed to higher macro-economic risk exposures and strengthen financial fragility. 　　Second, in the elderly-dominated society, the central bank’s tolerance for inflation rate has decreased, and interest rate adjustments are more likely to approach the lower limit. Once these new weighing factors are superimposed on the cycle, they will further complicate the operation of the monetary policy. The Central Bank must not only prevent the spread of inflation, protect the economic interests of the elderly, but also prevent the " hard landing” economic risks caused by excessive tightening. Objectively, the frequency of policy switching will exceed the previous level, and unconventional monetary policies will probably become the norm. In terms of stabilizing the economy and finance, the lack of effective demand caused by population aging has weakened the effectiveness of traditional monetary policy operations. Severe aging may further trigger liquidity traps and no longer be affected by loose monetary policies. Low interest rates are stimulating investment and consumption. The role is limited. Enterprises no longer pursue profit maximization but minimize debt. As a result, the demand for bank credit is insufficient and the liquidity of the central bank is difficult to release. Under such circumstances, structural reform will become a necessary supplement to the monetary policy.　　Third, increasing the proportion of working population and maximizing the negative effects of accelerating population aging can greatly improve and increase the effectiveness of fiscal and monetary policies. The loose population policy does not necessarily change the demographic structure and promote economic growth in the short term. The economic problems brought about by population aging are a rather complicated social project. It is not simply a matter of " opening up policies and stimulating fertility” that can open the door to alleviate the aging population. Moreover, increasing the labor participation rate will increase the proportion of the working population to a certain extent, effectively increase the supply of labor force, and reduce the tax burden on each of the young people. More importantly, increasing the labor participation rate can effectively increase the labor supply, not only helping to ease the burden of government pensions and guaranteeing the reliability of the pension system in the medium term, but also helping to reduce macroeconomic fluctuations, expand fiscal and monetary policies to create more space for operations, stimulate private consumption and investment, and drive economic growth.