The modern urban theory originating from the West cannot explain all characteristics of the ''Global South Cities'' represented by China. To make the urban theory more inclusive, this paper focuses on the spatial structure and dynamics of high, middle, and low class/income groups, and attempts to capture not only the localism and differences but also the general characteristics of cities through a comparative study of urban social space in three typical cities in China and the United States, namely Shanghai, Chicago, and Los Angeles. The results show that the Chinese cities is characterized by ''the low-income in suburbs and the high-income in the city'', which is opposite to the classical pattern of ''the upper class in the suburbs and the lower class in the city'' in American cities. The neighborhood dynamics in the United States are characterized by more ''downward social space'' in suburbia as well as a growing upward social space in the city. But the Chinese city is characterized by more ''upward social space'' due to the expansion of middle-income neighborhoods in the suburb, and a slight tendency of inner-city gentrification. The differences in urban socio-spatial structure between China and the United States are produced by the distinctions of various socio-economic factors. However, the general characteristics are also be found. The urban socio-spatial structure of each country is corresponding to the urbanization stage, and the differences in the structure and dynamics of social space can be understood by a unified analytical framework of the attractiveness of urban residents and the accessibility of intra-urban transportation. Moreover, the underlying mechanism of the urban socio-spatial dynamics is also similar, which reflects the extension of uneven development of social status in urban space and the spatial manifestation of the success of the dominant group in the locational competition in nature.

Keywords： comparative research; urban social space; Shanghai; Chicago; Los Angeles