Soil and water loss is serious in the Wuding River Basin, so soil conservation service becomes the primary ecosystem service. Based on SWAT model and GIS, the balance between supply and demand of soil conservation service and spatial flow path were analyzed to reveal the spatial matching characteristics and spatial flow mechanism of soil conservation service in the Wuding River Basin. The results showed that there was a strong consistency between the supply and the demand of soil conservation service in the Wuding River Basin, and both of them showed a trend of fluctuant increase and had a strong correlation with precipitation. The supply and demand in August 2001, July 2013 and July 2017 reached the larger value in all the months from 2000 to 2020, with the supply exceeding 2.5×10⁸ t and demand exceeding 3.5×10⁸ t. Correspondingly, the monthly average precipitation also reached a large value in these three months. From 2000 to 2020, the deficit months were more than the surplus months, and the deficit was increasing. The middle and upper reaches were in surplus, with the supply slightly greater than the demand, while the middle and lower reaches were in deficit, with the demand far greater than the supply. The spatial flow path of sediment reduction service was simulated. On this basis, the flow and benefit of sediment reduction service in each subbasin were obtained. The fluctuation of sediment reduction service flow increased from 2000 to 2020, especially in the downstream area in 2020. The benefit of sediment reduction service had accumulative benefit in the basin and showed an increasing trend during the study period. The results could provide a new perspective for the control of soil erosion in watershed, and have important reference value for ecological restoration and policy making of soil and water loss control.