Study on Standard of Population Aging

Do an increase in ageing in developed countries and ＂getting old before getting rich＂ in developing countries indicate that fluctuations in the population age structure have produced a qualitative change？ What is a qualitative change and what is a quantitative change＇？ Here we propose a new concept of Shadow Population,then establish a new standard for evaluating population age structure,finally present a typical five stage population age structure type transition model. The model simulation shows that all world regions are still in the adult stage and that population ageing belongs to the category of quantitative change. However, sustained low fertility will lead to a qualitative change in the ageing population. The current pressure of population aging in the adult stage placed on the pension security system shows that this system is truly not retirement age and Long-term stability in a sustainable system,Gradually raising the replacement fertility is the key to solving the socioeconomic development dilemma presented by future population ageing in low fertility regions or cotlntries,but the latter is more urgent.