The vigorous implementation of the one-child population policy led to a sustained decline in China’s fertility and birth rates. In the early 1990s, the country transited to the low birth, low mortality, low increase model, and new developments appeared in population quantity, quality, and structure. This does not mean that the population policy has completed its historical mission and can now be dispensed with; if we believe that the population policy is still required because it plays an essential role in socioeconomic development, then we must understand the general population trends of the twenty-first century, especially its first 50 years.