Abstract: The study of urban social living space is the main subject of urban social geography. The present study of urban social geography in the west have turned to the evaluation of social living space, and one of its cores is the study of the spatial structure and the basic urban social living conditions as well as the distribution laws of communities. The urban social income-space constitutes one basic part of the quality of the urban social living space. This paper, firstly, generalized the relating theories of urban social income-space abroad, summarized the economic and social foundations of the differentiation of income-space, and tried to explain the impetus of the differentiation of income-space. Secondly, it is the first time that took the facts of Xi'an into consideration, tried to research the urban social income-space and its patterns comprehensively in Xi'an, meanwhile to classify the pattern of social structure of income through different social income ranks, and to evaluate the regional differences of the social income-space through the imbalance index, to summarize the spatial structures and models of the social income imbalance. Thirdly, in methodologies, it adapted the method of behavioral sampling and at the same time used the theory of the substitution between social living space and social income-space. As the urban social space of income is the indicator of the quality of the urban social living space, so the author tried to discover the quality and structure of urban social living space through summarizing the space preference surface of the urban residents in Xi'an.