Data from the four population censuses since 1982 reveals the state and changes of China's urban household structure in different institutional environments. In the early stage of the reform and opening up when the planned economy system was dominant, household nuclearization tended to be prominent according to the 1982 and 1990 census data. Relaxation of the migration policy led to reduction of single-parent households, and the birth control policy promoted growth of couples households. Under the socialist market economy system after 1992, the types of household registration of urban population became diversified，and the welfare housing system began to transform into commercialized housing system. Based on the 2000 census, nuclear household continue to be of a high proportion，but the tendency of household nuclearization is restrained. After 2000, the birth control policy, elderly social security and housing reform have had profound impacts on urban household structure.

 Data from the four censuses since 1982 show that there are both similarities and differ- ences in the household structure between urban and rural married people at different stages of their life course. In urban areas，the majority of newly married people had established independent living u- nits. After giving birth to the first child，women mainly lived in nuclear households. When children grew up and became married，the proportion of the " empty nest" household among the elderly couples in- creased considerably. A gradually growing trend was observed in the widowed elderly living alone. However，widowed elderly living with their married children still accounted for a larger propor- tion. Before 2000，the household structure of rural married people was similar to that of their urban counterparts over their life course. In 2010，the proportion of newly married people living alone was low- er than that in 2000. The proportion of nuclear households declined for those married people who just had the first child，while the proportion of young married people living with parents or parents in law in the lineal household increased.

Intergenerationalfunctional relationship is an institutional system including obligation，responsibility，right to inheritance，mutual exchange and emotional communication．In the era of the contemporary social transformation，parents spend more money on their children’s education than in the past．Instead，adult children spend less cost to support their elderly parents than in the past．The obligation for adult children to take care of their parents is relatively reduced，but the elderly parents who could not take care of themselves have to mainly depend on their adult children．With the only child growing up，the daughter’s role is increasing in the intergenerational functional relationship，and even has no alternative．On the other hand，as the prolongation of life expectancy and increase of generations of lineal members，this will likely increase the burden of the adult children caring for elderly．Overall，at present，adult children's feedback function has declined and will directly affect the reproductive behavior of couples at childbearing age．The reasons for the weakening intergenerational functional relationship are as follows: social welfare system has played a role as an alternative to son in supporting the elderly，some objective factors have limited the play of family function，subjective consciousness of keeping intergenerational relationships has been weakened，the new institution environment that maintains intergenerational relationships has not been established．

In contemporary China，lineal families with three generations have been a typical family formation since the early 1980s. However，this trend differs between urban and rural areas. When children growing up in urban one-child families，especially after their marriage and childbearing，most of
them would not change their preference for a small family. In rural areas，the number of families with only one son has increased since the early 1980s. When growing up，most of those sons work outside the villages. Once getting married and bearing child，they need help from their parents for housework
and childcare. Since such family arrangement is beneficial to young people，its proportion has increased. The majority of the householders of lineal families with three generations were in the middle and early old age in 2010 and their family function of supporting elderly has been weakened. More than half of the lineal families with three generations have no members aged 65 and above in 2010. At the same time，the infant proportion of the lineal families with three generations has gradually increased since the early 1980s. The function of taking care of children has been enhanced in this kind of family.

Under the private land ownership before the land reform,nuclear family,while it was the biggest family type,wasn’t the overwhelming majority.Although taking the second place,lineal family type accommodates the greatest percentage of population.Composite family ranked the third,and about a quarter of village population lived in this family type.Impact of the collective economic system on family structure was that the family head was deprived of their control power over land and other basic production means,thus they lost their ability to restrain son’s demand for family division.Composite Family gradually decreased and finally disappeared.Nuclealization of family was achieved in the late 60s and early 70s of the 20th century.Labors of the investigated village began to engage in non-farming activities,but most of them didn’t leave families,and transition to non-agricultural employment of villagers has not had a major impact on family structure.At present,arrangement of meal and residence rotation of the elderly parents with two or more sons is universal in the village.Parents who are in meal and residence rotation periodically attach themselves to a married son’s family and form a intermittent lineal family,and at the same time rotary lineal families are formed.This type of families is specifically designated,reflecting special features of lineal family.