The article provides a theoretical analysis of a unique Chinese phenomenon - families of "left behind children". Based on statistical data on the population in China, the authors show the reasons why the phenomenon of abandoned children arose. These reasons are the change in the ratio of the urban and rural population, the dynamics of the number of marriages and divorces, the transformation of socio-economic life and the deep differentiation between urban and rural areas, contributing to the transfer of rural labor to cities. The authors define the phenomenon of abandoned children in China as a large-scale socio-economic phenomenon resulting from a change in the structure of the population and the gap between urban and rural areas, as well as labor migration from rural areas, in which rural children cannot migrate with their parents at the same time; this leads to the fact that children are separated from their parents and remain under the long-term supervision of grandparents, relatives or friends. To analyze the phenomenon of left behind children, we use the theory of structural functionalism, which provides theoretical support for the horizontal and vertical systemic structure of the Chinese social system; the theory of social conflict, which explains the conflict between the state system and the needs of people, as well as the conflict of interpersonal relations in the families of left behind children; the theory of social stratification, which provides an approach for analyzing social stratification and studying the place in it of families of left behind children. For the theory of social stratification, the authors considered the following dimensions of stratification: income, professional resources, cultural resources, social relations resources, prestige resources, civil rights resources.