China is at the late stage of modernization with rapid population ageing, in which multigenerational relationship family network has become normal. Multigeneration relationship family network has a richer meaning than the tradition definition of family, and is also functionally important. Based on the social network analysis, six typical families are studied. It is found that the physical space and virtual space of family network are overlapped, and the spatial dispersion does not cause the psychological separation among family members. The multigenerational relationship of family demonstrates a variety of network types including complete solidarity, double axis solidarity, basic solidarity, partial solidarity, and differentiation. The content and direction of family intergenerational support are diversified. The flow direction and amount of different resource types are dissimilar, and the center of family relationship network and the connection mode among generations are also different. The reciprocity of family intergenerational relationship does not happen immediately, and the reciprocity would be more meaningful when it spans over individual life cycle and family life cycle.

Using total fertility rate (TFR) of below 1.5 for over 20 years as the criterion for judging the low-fertility trap, this research examines the trend of fertility change in 66 countries and regions that entered the post-transitional stage before 1997. Three main findings are as follows: First, the low-fertility trap is not accidental; the risk of low-fertility trap has spread from 22 countries and regions to other parts of the world. Second, the low-fertility trap is not inevitable. There are 21 countries and regions where TFR has never fallen below 1.5, and most of them have remained above 1.7 or 1.8 in most years. Third, the low-fertility trap is not unescapable, but only a small number of countries and regions have succeeded. China has long stood and fluctuated at the critical level of the low-fertility trap, the average fertility intension level is significantly lower than the replacement level, and other demographic factors that have a negative impact on fertility have strengthened, there is a high risk of falling into the low-fertility trap.

Based on multiple survey data, the paper analyzes the situations and characteristics of family care arrangements for children aged 0~5 in China. Conducted by different organizations between 2010 2014, the multiple surveys show high childcare deficits, heavy burdens of mothers, imbalanced responsibility between motherhood and fatherhood, and a high proportion of childcare by grandparents. These problems not only directly affect the healthy growth of children, women??s employment and development, and the quality of family life, but also affect the implementation of the two-child policy. One of the key reasons of these problems is the lack of institutional support for childcare, particularly the shortage of formal care for children under age 3. “Work-family” balance has become a universal and rigid social needs. From a macro point of view, childcare is a necessary condition for population reproduction. From the perspective of family policy, it is necessary to extend the paternity leave and parental leave, to develop formal care agencies for children aged 0 ~ 3, and to promote the balance of workfamily for childcare givers.

By constructing the index of " elderly care dependency ratio" from a macro perspective， this paper examines the relation between supply and demand of Chinese elderly care resource and its trends，and discusses the characteristics of Chinese elderly care burden based on international comparisons．While the burden of caring for elderly is still in a very mild stage，there are significant differences in the levels and patterns of elderly care dependency among China’s provinces and between urban and rural areas．Looking into the future，the burden of caring for the elderly in China will continue to in- crease，stepping into a heavy-burden stage in the 2030s and a super heavy-burden stage in the 2040s． Therefore，institutional arrangements in a long-term perspective are needed in coping with an ageing society．

Abstract: The European Debt Crisis is a systemic imbalance among the European population structure，economic structure，welfare structure and political structure In the low fertility trap ，the high degree of aging and heavy dependency ratio fundamentally shake the population basis of welfare socie-
ty，while the European debt crisis expands the impacts of population structural changes from the economic field to the social and political fields European debt crisis is also a warning for China， where demographic，economic and social structural changes have been rapidly undergoing Under the circumstance of multiple challenges resulting from the combined complexity of an aging population，the increasing dependency ratio，slowing economic growth，the threat to middle － income trap，social transformation and reconstruction of social interests relationship， how to learn lessons from the debt crisis and to establish incentive and adaptive social institutions to coping with future population changes would be vital in making strategic choices of social development in China.

As the basic unit of human society，the normal functions of families represent an important prerequisite for the development of society．Development capability of family is the ability to meet the living and development needs of each family member，mainly including six capacities of support，economic ability，learning，social interaction and risk response，which can be achieved through two ways of intra － family construction and external social supports．However，with the process of weakening， transformation，externalization and socialization of family functioning，there are emerging new trends about families that corresponding structural imbalance between the needs and function of families and mechanism failure of self － supply and demand balance，as a result family capacity building depends on more external supports now than past．Therefore，we should focus on changing of the family' s core function and the difficulties faced by families，take family as a basic unit of social policy，actively build a family － friendly social environment and institutional support，thus fully promote the development capacity of family．

From the logical starting point of corresponding structure of the risk factors and protective factors and drawing on the perspective of resilience theory,this paper,by situating Left-behind Children and Migrant Children into the same analytical framework,found that the two groups of children,while unique,share more similarities.They both reside in a growth environment without certain protective factors,which enlarge the probability of risk factors.Based on the exploration of risk factors faced by Left-behind Children and Migrant Children,this paper proposes a policy orientation of "the maximum protection and minimum limits",which improves protective factors,and enhances risk prevention mechanisms by eliminating institutional barriers,and building family development capacity.

From the perspective of the relationship between collective rationality and individual rationality, and collective behavior and individual behavior, this paper takes China’s 34 public policies on governing imbalanced sex ratio at birth(SRB) as examples to analyze public policy’s expression, functions and effects at the individual level. The analysis is done based on the theoretical framework of individual behavior pattern and using content analysis method, and it involves in individual behavior, including dimensions of cognition or attitude, emotion and behavioral intentions. Analytical results indicate that current public policies cover different dimensions of individual behaviors and shape guiding mechanism for individual behavior changes, but with imbalanced impacts and shortage of motions and influential channels. Furthermore, the paper explores the "Pareto improvement" path of individual reproductive behavior changes in line with the public policy mechanism to promote the normalization of high SRB, proposes public policy basis should be changed from "control-orientation" to "support-orientation".