Abstract: Most of the existed researches of population distribution are based on single megacity and concentrate on few megacities like Beijing, Shanghai, Guangzhou, Hangzhou, et al. However, few researches consider in detail whether there are some common and specific population distribution laws in and between all the Chinese megacities. This paper tries to answer the question by analyzing the spatial population distribution, evolution and polycentricity of 12 megacities above the vice-provincial level in China, including Beijing, Shanghai, Tianjin, Chongqing, Guangzhou, Shenzhen, Nanjing, Hangzhou, Wuhan, Xi'an, Shenyang and Harbin. Quantitative indicators including Inequality Index, Moran Index and Polycentric Index were used in our analysis to indicate the inequality, agglomeration and polycentric character of population distribution in Chinese megacities. According to the results, the total population of almost all the Chinese megacities kept growing from 2000 to 2014. Meanwhile, the gap of total population between different megacities shrank from 2000 to 2014. The population distribution overall kept balance among different megacities but concentrated in some specific local region like some downtown districts for a single megacity. Most of the emerging region were around the high density population area, which means the megacities were more likely to expend continuously close to the inner suburban district. Both the obviously high and increasing spatial agglomeration processes and diffusion processes were found in the population distribution and evolution process in megacities from 2000 to 2014. The polycentricity of population in different megacities varied, Shenzhen, Chongqing and Harbin showed obvious polycentricity, Beijing, Shanghai, Guangzhou, Wuhan, Nanjing, Hangzhou and Xi'an were changing from single center to multicenter, Tianjin and Shenyang showed inconspicuous single center with population concentrate in very few downtown districts. The polycentric tendency of most megacities was weakening along the time. Generally speaking, through a broad and systematic research about Chinese megacities, this paper makes the common law and specific law of the population distribution more clear, which also provides some useful suggestions for the megacity development and planning.

Key words: population distribution, spatial structure, polycentric, megacities