Water yield calculation and mapping are of great importance to water resource planning and management and hydropower station construction. A water yield model based on InVEST was employed to estimate water runoff in the Xitiaoxi River basin. The data included land use and land cover, average annual precipitation and potential evapotranspiration, soil depth, and plant available water content. In order to test model accuracy the natural runoff of Xitiaoxi River was estimated based on linear regression relation of rainfall—runoff in a ‘reference period’. After repeated validation, when the Z value was 6.5 the water yield was 8.30 E 8 m³ and this was a smaller difference with natural runoff. From the distribution of water yield, south and southwestern areas of the watershed had higher water yield volumes per hectare.