Urbanization has a profound impact on soil carbon recycling. Based on spatial specific sampling of the urban soil and inversion of the urbanization history of Nanjing between 1900 and 2010, spatio-temporal relationship between spatial distribution of inorganic carbon in urban soil and urbanization processes was analyzed for assessment of inorganic carbon sequestration potential of urban soil. Results show that inorganic carbon density of the urban soil is closely related to history of the city, and it much higher in historical old regions than in newly urbanized regions, which indicates that the urban soil is highly potential in sequestration of inorganic carbon. The mean inorganic carbon density in the urban soil grows linearly with the development of urbanization. The inorganic carbon pool in the topsoil of the urban area studied reached 2.94 Tg and the area still had a potential of sequestrating1.45 Tg of inorganic carbon in future. All the findings in this study may serve as theoretical basis for elaborating the mechanism of carbon recycling in the urban system and conducting research on inorganic carbon sequestration in urban soil.