Research on the distribution characteristics of urban soil carbon and nitrogen density and their influencing factors will help further understand the relationship between urban soil carbon，nitrogen cycles and human activities under the background of rapid urbanization.Taking the urban topsoil in Nanchong city as the research object，the distribution characteristics of urban soil organic carbon and nitrogen density were analyzed from multiple perspectives.The results showed that soil organic carbon density in surface soil was between 3.78 and 110.49 t·hm-2，and soil nitrogen density was between 1.19 and 6.54 t·hm-2，and both decreased with the increase of soil depth.The soil organic carbon density decreased significantly in an order of broad-leaved forest>evergreen forest>shrub>herb under different vegetation types，and there was no significant effect of vegetation type on soil nitrogen density.The average soil organic carbon density was significantly different among different types of green space，following an order of park green space>road green space>protective green space>affiliated green space>street green space，and there was no significant difference in soil nitrogen density under different types.The soil organic carbon density of green land in different functional areas had no significant difference，while the difference in soil nitrogen density was extremely significant with the order of culture and education area>commerce area>industry area>residence area.The soil organic carbon density increased with green space age，however，the soil nitrogen density firstly increased and then slightly decreased.The spatial differentiation of urban soil carbon and nitrogen densities was the result from interaction between natural and human factors.Human disturbance factors were the main reasons for the changes in soil carbon and nitrogen densities under different vegetation types，green space types，functional areas and green space ages.