Abstract: Using the entire data set from Shenzhen RuralUrban Migrants Survey in 2005， this paper analyzes the cohesive subgroup structures in the ruralurban migrants' social support networks （including instrumental， emotional， and social contact support networks） and social discussion networks （including marriage， childbearing， contraception， and oldage support networks）. The results indicate that the phenomenon of subgroups is widely exhibited in these migrants' social networks， and such subgroups overlap to a great extent. The overlapped subgroup structures in the social support and social discussion networks are helpful not only to the migrants' social integration into the urban communities， but also to the expansion of the new culture in regards to marriage， childbearing， and oldage support.

Key words: cohesive subgroup, rural-urban migrant, social network