The government set a policy about the number of children. The one-child policy successfully implemented in China in 1979. That is the first time to start for seriously control amount of population. We will exemplify the country that most of population “China”. They allow to having a one child per family. If the first child is female, they allow having two children. Father and Mother of the family are only child, they allow to have two children in their family. The government of China legislates for violators to fine money follow their net income. In 2013, the one-child policy is relaxed to the two-child policy because of many problems. The problems of one-child policy are increasing of the elderly and men. These are lead to unbalance of population. At present, the countries that use two-child policy are China, United Kingdom, India, Hong Kong and Vietnam.