Here 38 sub-catchments in Yellow River Basin have been selected to explore the driving factors for runoff decline in this region. Climate elasticity and landscape elasticity which indicate the sensitivity of runoff to climate and landscape change are calculated based on the catchment water-energy balance equation. Furthermore, we quantify the effect of climate and landscape change on mean annual water yield. Results show that the distribution of climate elasticity is consistent with landscape elasticity and regions with highest sensitivity is located in the Loess Plateau. The annual runoff had statistically negative trends in most study sub-catchments. Landscape change is the dominant forcing factor for runoff decline in most study sub-catchments, specially in the Loess Plateau. By the analysis of NDVI (Normalized Difference Vegetation Index) during recent thirty years, we find that the improvement of vegetation is the dominant changes in landscape. This research indicates that it is a effective and promising application approach to quantify the effect of climate and landscape change on annual water yield based on the catchment water-energy balance equation.