Continuous and complete population data by age and education level are the basis for studying the dynamic relationship between population and economic and social development in a country or region. However, in non-census years, such data cannot be directly obtained or its quality cannot be guaranteed. To this end, the national population census data from 2000, 2010, and 2020 are used to reconstruct the population data by age and education level for non-census years from 2000 to 2020 using the population discrete development equation forward and backward bidirectional feedback fitting method. Based on this, an improved accounting model is used to calculate the human capital stock from 2000 to 2020.The research results show that the difference between the reconstructed non-census year total population data and the adjusted data from the National Bureau of Statistics is very small. The reconstructed age-specific population data corrected the bias in the age composition data published in previous statistical yearbooks. The calculated data on human capital stock shows that it increased from 15.856 billion person-years in 2000 to 26.479 billion person-years in 2020, with an average annual growth rate of 2.60%. Affected by the ageing population and the decrease in the working age population, the growth rate of human capital stock shows a decreasing trend between the first and the second ten-year periods.

 In the process of building a modern country, China is witnessing major changes unfolding in our world, something unseen in a century. China is also facing challenges such as rapid population ageing, negative population growth and a decline in labor force that would largely impact its socioeconomic development and comprehensive strength. Based on a renewed understanding of the population development and its relationship with socioeconomic development, this paper discusses the state of population development needed to enhance the country's economic strength. It also proposes the scope and direction of China's longterm population development in the future, emphasizing the central and fundamental position of population size. To be specific, the desired population size should be between 0.9 and 1.2 billion by the end of this century. Actively changing the longterm trajectory of population development, raising the fertility rate close to the replacement level and keeping the population size between 0.9 and 1.2 billion would also improve the population structure, quality and spatial distribution, strengthening the economy.

China's population will start to drop and age rapidly in the third decade of the 21st century. This negative population growth brings various challenges to China's future economic development. To sustain the economic growth and development, it is necessary to explore theoretical basis for the driving forces and new paths for further economic development. Reflecting on the limitations of existing theories of population and economic development and drawing on their enlightenments and metaphors, this research demonstrates how population size interacts with economic development. Further, this study proposes the concept and theoretical framework of population cushion, which can act as a new driving force of Chinas economic development in the context of negative population growth in the future.

This paper uses the data of the seven northern provinces and cities in the 2017 China Fertility Survey, to assess the fertility status and actual fertility level in China, particularly in the northern provinces, with total fertility rate, parity progressive total fertility rate, lifetime fertility rate, and fertility patterns (age patterns of marriage and childbearing). The results suggest that the fertility level in China is indeed at a moderately low fertility level between 1.5 and 1.9, but not at a very low level. The twochild policy has a significant effect on the fertility of the second child. Parity Progressive desired fertility tends to more truly represent the actual desired fertility. According to the parity progressive desired fertility at ages 20~29 and 30~39, there is a possibility of increase in future fertility in China.

The development of regional economy depends on the regional central cities and the accumulation of human capital. Therefore ,the construction of the central city becomes the growth pole of regional development. It plays a significant role in regional economic and social development,and human capital accumulation is the key to realize its functions. How does central city enable the human capital accumulation? In this paper,we establish spatial econometric models to explore the effect of the central city on human capital accumulation,from the aspects of economy,industry,education,employment and medical service. It is found that the industrial development,public expenditure,education and medical care have significant impacts on regional human capital accumulation. The impacts of central cities on regional human capital accumulation shows different mechanisms,some are accumulation, while others are spillover. Therefore, development strategies of central cities should be formulated to take into account both their own economic development and the interaction among cities,ultimately achieving common development.

China’s universal two-child policy will definitely impact the future development of population．This paper identifies the target women of the universal two-child policy by family type，fertility history and fertility intention，according to which we calculate the number of extra births and related fertility rates and patterns．Scenarios of population forecast are developed using the model of the parity progressive population dynamics．Results show that the universal two-child policy would produce additional 21 million population during the 13th Five-Year Plan period．The population peak would be postponed to 2030 standing at 1.47 billion，slightly larger than the scenario without adjusting policies．Meanwhile，decline in population and labor force would slow down，and labor supply would increase while the pace of population ageing decrease after 2035．However，the long-term declining trend of the total population would not change．China’s population would continue to shrink at an average rate of 6.4 million per year after 2030，and will be reduced to 1.02 billion by the end of the century．

This paper investigates the regional consumption function of China's provinces based on the panel data of 31 provinces from 2000 to 2010，in order to explore the effects of demographic factors on regional consumption. The results show that demographic variables such as the level of urbanization and schooling，the inflowing rate of external population，and the degree of aging have significant impact on the regional consumption. Apart from this，the influences of demographic factors on consumption vary from place to place，which is caused by the discrepancies of population effects among regions.
Thus，we draw the conclusion: at the regional level，the lagged development of urbanization hinders the expansion of consumption and domestic demand; the unevenness of educational level prevents the optimizing of consumption models; the aggregation effect of transient population promotes the consumption level; and the full use of age structure unleashes the regional consumption advantages.

This paper analyzes death underreporting in China＇s population censuses with a reestimation of levels and patterns of mortality since 1990．There is severe death underreporting at ages 0-4，more notably in the 2010 census．Death reporting is also rather incomplete at ages 60 and over． Death probabilities are reestimated by age and sex from which life tables are reconstructed． Over the last 20 years，life expectancy at birth has increased from 67.33 to 71.58 years for males and from 71.70 to 78.26 years for females，respectively．Pace of mortality improvement has been more rapid in the recent decade that in the past．

Balanced development of the population is the key determinant of the construction of a conservation-oriented and environment-friendly society.The family planning policy,beginning in the early 1970s in china,precipitated fertility decline,inhibiting the excessive population growth and facilitating the harmonious development of the economic and population growth.China has had low fertility for more than 20 years.Imbalanced development of population under the long-term low fertility generates more complicated population phenomenon,causing conflicts between population size and structure,labor supply and demand,and migration and regional development.Addressing these population challenges is central to the construction of a population equilibrium society.

The purpose of the paper is to resolve the issues of the data quality of working people when used as an indicator of labor input in production function, and find out a viable method to re-estimate human capital stock and composition of educational level of Chinese working people in three industries .As a result , we provide the basic data for more accurate analysis of productivity and growth of three industries.