The sustainable development of cities must make use of principles of social justice and social efficiency to manage population replacement and fusion in a balanced way.

First, let us consider the population development replacement system. A city cannot develop without population mobility. There is no question that this is needed, but there is much debate about how to ensure it is safe, orderly and effective.

The second consideration is the issue of fusion. A city's ability to absorb the mobile population in a harmonious way reflects the openness of its attitude and its degree of social acceptance. The more a city discriminates against migrants, the more offended and more offensive they will become, resulting in a psychological confrontation between permanent residents and migrants.

In contrast, the more tolerant a city is in terms of its culture and policies, the more positive the effect of migrants will be.

The third aspect we must consider is the population development safeguard system. On the one hand, we should reject urban-rural discrimination, and we need to recognize the gap between the city and the countryside and the need to face up to cultural conflicts between permanent residents and migrants.

On the other hand, we should provide equal treatment to the floating population in terms of safeguarding their rights and providing them with opportunities in order to realize sustainable urban development in the spirit of coexistence, communion, co-establishment and the creation of a society which benefits all of its members.

Fourth, we need to ensure balance in population development. The growth of the urban population must be balanced against the ability of resources and the environment to support this growth. The updating of industrial structures and the adjustment of labor-intensive industries, or even adjustments in the geographical distribution of industry, mean that the market economy is playing a proper role in regulating the flow of population. There is no doubt that industrial policies have a strategic guiding effect on population development.

Therefore, population development in big cities needs to be taken into consideration when reviewing the overall situation of the country. China's hukou (household registration) system is entrenched and requires constant examination and continuous change.

It is time to comprehensively regulate and reform the county's population policies. The formulation of a system of "population governance" will better meet the requirements of comprehensive, coordinated and sustainable development than any form of "population control." The basic idea of modern population governance is not only conducive to moderate population growth, but it also improves the quality of the country's population, creating a more reasonable population structure and ensuring more effective population migration.

The writer is a professor at the Institute of Population Research of Peking University.

This article was translated by Li Jingrong. Its original version was published in Chinese.

Opinion articles reflect the views of their authors, not necessarily those of China.org.cn.