Abstract: In order to evaluate the effectiveness of soil and water conservation in the water source area of Middle Route of South-North Water Diversion Project, as well as provide scientific basis for formulating soil and water conservation measures at the present stage, the remote sensing data were used to study the changes in ecosystems in the water source area from 2010 to 2015, including 39 districts and counties, and the spatio-temporal distribution in soil retention capacity was also assessed using the InVEST model. The results show that, through implementing forest-grass measures, comprehensive management of small watershed and other ways, the areas and landscape patterns of natural ecological lands in water source area have been improved and optimized from 2010 to 2015, and the effects of soil and water conservation control were achieved, which mainly seen in three aspects:(1）The area of “sink” landscape types, such as wetlands, shrubs and forests that alleviate sediment loss, increased by 11.49%, 0.29% and 0.11% respectively, while their connectivity increased and fragmentation decreased. The areas of “source” landscape types, such as farmland and bare land that promote sediment loss, decreased by 2.24% and 2.39%, respectively, while their connectivity decreased and fragmentation increased.(2）The restoration effect of vegetation was quite good, and the average vegetation coverage in the water source area increased from 63.06% to 72.33%.(3）The average soil retention capacity per unit area of ecosystem enhanced by 2.74 t/hm2, with an increase of 0.73%, and the areas with improved soil retention capacity accounted for 79.34%. More attention should be paid to the management of the soil retention capacity in the agricultural plain areas with highly dense population distribution such as Hanzhong Basin, Danjiangkou reservoir area, central and southern Xichuan, where the spatial connectivity of cultivated lands and bare lands can be reduced by implementing hedgerows and planting fruit forests having economic benefits, thus to enhance the soil retention capacity.