Abstract: Riparian wetland construction serves as a critical measure for ecological urban watershed management. However, existing studies have predominantly focused on its impacts on water resource endowment, while the soil carbon sequestration potential of urban riparian wetlands remains overlooked. This study investigated the Xinxu River riparian wetland in Nanning, China, by analyzing the spatial distribution characteristics of soil organic carbon density across 0-50 cm depths at 30 sampling sites. The objectives were to clarify the spatial patterns of soil organic carbon density and identify its key drivers. The results demonstrate that: (1) soil organic carbon density in the Xinxu River wetland ranged from 1.42 to 2.49 kg·m^-2, with a mean value of 1.89 kg·m^-2; (2) Vertical heterogeneity in soil organic carbon density distribution was significant: surface soils (0-10 cm) exhibited irregular patchy clustering, whereas deeper layers (>10-50 cm) followed a belt-shaped gradient aligned with river channels; (3) Anthropogenic activities explained 73% of the spatial variability in surface soil organic carbon density, while natural factors deeper layers, contributing 36.5% to soil organic carbon density variability in the Xinxu River wetland; (4) Total phosphorus, total carbon, total nitrogen, cation exchange capacity, temperature, and elevation were identified as key environmental factors of soil organic carbon density. These findings provide critical data to inform conservation strategies and management policies for urban riparian wetlands, emphasizing the need to reconcile anthropogenic interventions with natural hydrological and biogeochemical processes in carbon cycle regulation.