【Abstract】In the long-term development process， not only does family structure form different structural patterns， but also the factors about the structural changes are constantly changing. The factors about the structural changes in family structure plays an important role in maintaining social stability. The system is based on literature research and comparative analysis to analyze the influencing factors of different family structures. It is concluded that the influencing factors of direct and core family structure changes have common points and differences. The government should formulate relevant policies from various angles. consider. In addition， public policy should pay special attention to inter-generational relationship maintenance and pension issues.
　　【Keywords】family structure; immediate family; nuclear family; public policy
　　【作者簡介】Xu Xin， Yunnan University。
　　1. Introduction
　　According to China Science Communication， family structure is the composition of family members and the state of interaction and mutual influenc. The factors that influence the changes in the structure of today’s major families are diverse. Since the 1980s， family structure has faced challenges from social and family internal affairs. Quite a few studies have been conducted on the mainstream factor including China’s social-economic development （Tong Huisheng， Song Dan 2016） and demographic factors （Yang Shenghui， Chen Wei 2007）. Some scholars have analyzed the population movements leading （Zhou Fulin 2016）. However， the considerable research has been devoted to phenomenological description and theoretical speculation， but rather less attention has been paid to comprehensive research and comparative analysis of influencing factors. This paper will find the coordination point between public policy and social family level through comparative analysis of the causes so that public policy can take into account the factors.
　　2. Common influencing factors
　　The implementation of the family planning policy in the early 1980s imposed strict restrictions on the population， which resulted in a large number of “Four Two One” families in China and effectively reduced the birth rate to some extent. A decline in the birth rate delays the childbearing age， and family membership will remain constant over a longer period of time.
　　3. the special influencing factors affecting the changes of the direct family structure
　　Judging from the 2000 national census data， the number of direct families in rural areas has increased a lot compared with previous years， which has a great relationship with the real environment. On the one hand， a large number of migrant workers are forced by real life pressures in the process of flooding into the city. They have to keep their children in rural homes and take care of the elderly in the home. On the other hand， the distribution of educational resources within the city is not balanced. Parents will send their children to their ancestors to help their children get better educational resources. 　　4. the special influencing factors affecting the changes of the nuclear family structure
　　According to the 2010 census data， the peak of the offspring is 10 and 40 years old. In the core family of middle-aged couples， children have begun to go to school， and their self-care ability is improved. From “Five Pu” and “ ccording to the data of Liupu， the proportion of nuclear families in the age group over 45 years old has risen sharply. This is mainly because their children are mostly due to study， work or marriage and leave the family， thus forming a large number of middle-aged or elderly ”empty nest families.
　　5. Conclusion
　　The factors affecting the change of family structure involve many factors such as economy， politics and culture. Therefore， when formulating relevant policies， we should consider it from multiple perspectives. A large number of young rural workers are pouring into cities leaving empty nests and left-behind children in rural areas. The uneven allocation of resources within the city has also caused different intergenerational members to live in different places. Both situations will lead to limited communication between the two sides. Therefore， public policy should pay attention to the system construction to guide the links between different intergenerational members. The policy assists the adult offspring and the elderly relatives to live in the same place. At present， China’s core family structure accounts for a large proportion， which is largely It is because children form a new family and live alone with their parents. This will lead to a weakening of the concept of family pension. Therefore， public policy should focus on the issue of social pension and guide the correct concept of social pension.