The crisis of aging population with lower fertility has occurred in many OECD countries owing to the decline in total fertility rate and the increase in life expectancy. According to the model of public pension expenditures and sensitivity analysis of its parameters, the gradual rise in the elderly dependency ratio will lead to the step-by-step increase in public pension expenditures in these countries, while the increase in retirement ages will result in the reduction in the elderly dependency ratio and be helpful for the control of the rapid increase in public pension expenditures. Accordingly, many OECD countries have carried out the reform of increasing the retirement ages. This paper makes a comparative analysis of the basic conditions (life expectancy, health life expectancy, education level of adults and the ratio of working-age population) and policy design of increasing the retirement ages in these countries. It sums up the main experiences as follows: the first is to adjust the retirement ages based on the enough consideration of the macro-economy and population conditions; the second is to increase the retirement ages incrementally and gradually in a certain period and set up the window period of the reform; the third is to establish the assistant mechanisms of increasing the retirement ages in order to avoid the economic efficiency losses of the reform, such as the policy of flexible retirement, and the promotion and protection policy for the old people's employment. On this basis, it discusses the conditions and policy design of increasing retirement ages in China.