Soil organic carbon (SOC), as the main body of land carbon pool, its distribution characteristics and spatial relationship with driving factors have significant impacts on the process of soil carbon turnover. Through field investigation, sampling and indoor analysis, based on the geographical weighted regression (GWR) model combined with nine environmental and soil variables, the spatial distribution of soil organic carbon and its main affecting factors in the Yihe River Basin were analyzed. The results showed that:(1) the distribution of organic carbon in the surface soil was between 3.37-38.34 g/kg. There were spatial differences in the upper, middle, and lower reaches, among which the difference in the upper reaches was the largest and the difference in the lower reaches was the smallest. (2) Soil organic carbon was closely related to the physical and chemical properties of soil itself, and was less affected by environmental factors other than annual average temperature. (3) The GWR model can predict the spatial distribution of soil organic carbon in the Yihe River Basin, and the local determination coefficient was between 0.49-0.64. From the downstream to the upstream, the determination coefficient increased gradually, and the prediction accuracy of the upstream was the highest. (4) In the middle and upper reaches of high altitude, soil organic carbon contents were mainly affected by site environment, soil parent material, and surface coverage. In the middle and upper reaches of low mountains and hills, human activities and environmental factors jointly affected soil organic carbon content. In the middle and lower reaches of plain area, the agricultural activities and chemical fertilizer input were the main factors causing high soil organic carbon content. This study revealed the spatial differentiation characteristics of the effects of various factors on organic carbon, which could provide a basis for the reasonable development and management of soil ecosystem in the Yihe River Basin.