Since ancient times, many knowledgeable scholars have put forward the view that population growth will be limited sooner or later. In the 20th century, especially after the Second World War, population control has been paid more and more attention. Since 1950s, cybernetics and system science have injected new ideas and methods into the study of demography.
Since 1980s, China scholars have actively applied the theories and methods of cybernetics and system theory to study population problems. 1985 The book Population Cybernetics published by cybernetics scholars Song Jian and Yu Jingyuan is the first monograph of this subject. In any country and any society, the population situation and population have their historical evolution process. There are four basic factors that directly affect people's state change: birth, death, migration and time delay. Among them, death, migration and time are factors that people can't effectively control, and only the birth rate is the parameter that can be effectively controlled. The research purpose of population cybernetics is to control the birth rate through family planning, so as to control the rapid growth of social population and make the population reach an ideal state.
The main research contents of population cybernetics include: various mathematical models of population system, definitions and calculation methods of various population parameters, dynamic characteristics of population system, stability of population system, controllability and observability of population system, prediction of population system, optimal control of population system, population goal and development process of zero population growth, etc.