A Study Of China’s Population Projections Based Of Fertility Transition Theory

China has been a population-rich country since ancient times,and population is one of the key issues in the socio-economic development of a country or region.Accurate population age structure projections are important decision-making data for future social development.Since the implementation of the "comprehensive twochild" policy,China’s fertility rate has briefly peaked,but in 2018 and 2019 the fertility rate fell below the lowest in history.Therefore,in order to ensure a balanced population in the long term,it is important to forecast the future age structure of the population.According to demographic theory,the key to population projections for a region lies in the following three factors-birth rate,mortality rate,and population migration rate.In view of this,combined with the special national conditions of China.This paper begins with a comprehensive analysis of the implementation of China’s population policy,the influencing factors and the final impact results.The total fertility rate and the age-specific fertility rate are projected through the fertility transition concept and the probabilistic population projection method.The prediction results show that China belongs to the third stage of fertility development,based on which the future trend of fertility level changes in China is predicted by a first-order autocorrelation model,and the final results are predicted in three scenarios: medium,low,and high.Second,the Lee-Carter model and historical data are used to predict the future age-specific mortality in China.Since the number of international population migration in China is small compared to the total,the impact of international population migration situation on population structure will not be considered in this paper.The future demographic structure of China is projected by the "PED" model with fertility and mortality projections for 2019 as the base period data.The results show that under the low and medium scenarios,China’s total population will reach its peak in 2025 and 2030 and then continue to decline,and the demographic structure will further "reduce the number of children" and "ageing".Under the high scenario,the number of newborns continues to increase while the proportion of the elderly population is relatively high,and the demographic structure is optimized and improved,which is a young demographic structure.The fertility policy only makes the total population of China increase,the fertility rate and population structure have not been effectively improved,and the premise presupposed in this paper is even fully open to fertility,which shows that the change of fertility concept has been deeply rooted in people’s hearts,and the stimulation of fertility rate in China by simple fertility policy will not have much effect in the short term.China’s fertility policy cannot just stay on a comprehensive two-child policy,and in the short term,the government further implements the fertility policy by adopting corresponding policies;in the long term,it needs to further make me secure the social pension system,improve the comprehensive quality of citizens,and raise the overall social welfare level,especially the protection of young children and the protection of pregnant women’s rights in order to fundamentally alleviate the demographic crisis facing China.