This paper summarizes stylized facts of three dimensions of population agglomeration and the radiation effects of central cities relating to the evolutionary laws of China's population distribution. We test with decennial census data from 2000 to 2020 to identify determinants of population agglomeration and radiation effects. The results show that the distance to the major ports, central cities, and city centers of central cities determines China's population concentration. Moreover, central cities have apparent radiation effects. The closer to the central cities or the larger the population and economic scale of the central cities, the more the population is concentrated in peripheral cities or counties.