Although the interethnic marriage among Mongolians, Manchus and Hans has been repeatedly relaxed and restricted in Chinas history, the contact and communication among them have never stopped. This study found that the interethnic marriage among Mongolian and Manchu people is prevalent that the proportion of interethnic marriage stands over 40% for both of them. The intermarriage between the MongolianHan and the ManchuHan was the mainstream. The highly politicized “ManchuMongolian marriage”, which lasted for about three centuries in history, has been replaced by free communication among ethnic groups. The proportion of Mongolian women who are interethnic married surpassed its counterpart of Mongolian men. In terms of spatial distribution, the three ethnic groups formed a distinct and extensive northeastsouthwest intermarriage chain based on the Liaoxi Corridor. During migration, interethnic marriages mainly occur between local men and migrant minority women. Economic interaction, settlement pattern and migration promote exchanges and interactions among different ethnic groups.

According to the 7th Population Census, the size of the floating population has further grown; the urban attraction to floating population keeps increasing; the floating population has become the leading factor of urban population growth; urban to urban population migration has expanded; the floating population is still highly concentrated to move to the eastern region; population who live in places other than their household registration areas has strikingly increased; the international immigration has steadily grown. In summary, highly active population movements in China get further confirmation.

Using data from China??s population census and one-percent national population sample survey since 2000,this paper analyses the changing patterns and challenges of child population in China. Results indicate that the child population has stopped decreasing and shows a sign of stabilization.Meanwhile,the number of children who grow up in urban areas is increasing while the rural number continues dropping. The proportion of ethnic minority children maintains a continuous growth. The proportion of families that have no children is also increasing. In contrast,the proportion of multi-child families keeps reducing. The living conditions and development chances of children are facing several challenges,including a large number of floating and left-behind children,especially the urban left-behind children,which have been gradually expanding. The imbalance of children??s sexual structure is also striking. Family care becomes an emerging problem and the compulsory education of children still faces severe challenges. Finally this paper discusses policy implications regarding poverty relief,market-driven family care system,and the educational problem of children.