The evapotranspiration (ET) is one of the most important components of the water cycle in semi-arid Taihang Mountain region of North China. Due to significant changes in topography, the ET of this semi-arid region tends to vary dramatically both in time and space, which renders the accurate estimation of yearly or seasonal ET a difficult task. In current study, based on rGIS-ET v1.0, a regional ET model, by adding module of adjusting surface temperature in terrain, solar radiance terrain correction, and shaded relief, we improved the rGIS-ET a remote sensing model on ArcGIS platform for mapping ET distribution in such a semi-arid mountain area. With DEM of 30 meter and climate data, we run the model to estimate daily ET in mountain area using Landsat data. The ET distribution pattern estimated from Landsat data by rGIS-ET v2.0, was integrated into SWAT method to calculated daily ET at a high spatial resolution in the sub-watersheds. With input of the daily ET, SWAT simulated the annual flow of the component of water balance at sub-watersheds from 1995 to 2003. The variations of flows of annual ET were significant amount the sub-watersheds and the variations of ET flow may cause the variation of other components flow.