[Objective] To explore the effect of ecological degradation and restoration on soil conservation function and its mechanism, and to provide a certain basis for decision making regarding ecological protection and construction in Three Rivers Headwater Region.[Methods] By building indices such as land cover condition to characterize the macro-ecosystem changes in headwater region, we quantitatively analyzed the effect of ecosystem changes on soil conservation function, and discussed its main mechanism.[Results] The ecosystems in headwater region experienced significant degradation and recovery process from 2000 to 2010. Soil conservation capacity of different types ranked as:forest land > cultivated land > high coverage grass > medium coverage grass > low coverage grassland > wetland > unused land. In the process of ecological degradation and recovery in the study area, the potential loss per unit area increased from 1.25×10⁴ t/hm² to 1.50×10⁴ t/hm² during 2000-2010, The actual loss per unit area increased from 3 200 t/hm² in 2000 to 3 500 t/hm² in 2005, and to 3 800 t/hm² in 2010. In the process of ecological restoration, the areas of high coverage grassland and wetland in Three Rivers Headwater Region increased, alleviating the trend of ecosystem degradation to some extent. Soil conservation quantity per unit area in Three River Headwater Region increased from 9 300 t/hm² in 2000 to 1.03×10⁴ t/hm² in 2005, and to 1.11×10⁴ t/hm² in 2010.[Conclusion] The types of land cover and vegetation coverage had important effects on soil conservation function, the ecological degradation and restoration of Three Rivers Headwaters Region were closely related to the change of soil conservation function.