Rural-urban migrant issues are always attached great importance by the Party and government. The emotions of the migrant workers cannot be ignored, especially their self-identity which refers to their integration into the urban society. It is of some creativity that researching the effect factors of the self-identity of rural-urban migrants from the perspective of social supports and social involvements. On the basis of the analysis of individual data from the 2013 survey of the assimilation of the floating population, we conclude that instrumental support, not social interaction support, exerts a significant influence on social involvements of rural-urban migrants; social interaction support, social instrumental support and social involvements influence rural-urban migrants’ self-identity significantly; social involvements may be a possible mediating variable between instrumental support and self-identity of rural-urban migrants.