An Analysis Of Factors Affecting Population And The Forecast Of General Trend

China's birth rate has been declining since1990s. With a low and stable death rate , our population variation is mainly determined by birth rate. Compared to other countries in the world, the fertility declines so rapidly which is such a low level that we never anticipated. The low birth rate of population is not just a population problem, but also be related with economy, society, culture and so on. The influence of factors on the birth rate differs in different times and spaces. Even within the same space, the direction and strength of factors affecting birth rate differs on different conditions. The research on factors affecting birth rate which make it keep declining since 1990s has great significance for China.Based on previous research fruits of birth rate, the paper firstly does some descriptive statistical analysis about the current condition of population in china which are the realistic basis of the empirical research. Secondly, the paper does analysis about the degree of the factors affecting birth rate based on time-series data and cross-sectional data. Finally, the paper conducts prediction of Chinese population size and structure in the future based on models based on Winbugs software, puts forward relevant suggestions.The main results concluded from the above research are: (1) Given an assumption of stable economic and social development, the birth rate will continue to decline. By 2026, our total population would reach its peak number of 1.4 billion to be followed by a gradual decrease. (2) The impact of family planning policy is not the significant factors causing steady declining of birth rate since 1990s. (3)Factors that affect the birth rate include the economic factor, education factor and people floating factor. (4)Aging index will exceed 100% in 2020. The economic development, population, resource, environment, and social security will be confronted with serious problem of population aging. Based on the conclusions, policy suggestions proposed are as follows: Rationally readjusting the family planning policy; China would redouble its efforts to solve the problem of population aging; A nationwide social security system would basically take shape by then; Establishing social security system conducive to floating people.