Jinghe River Basin was chosen as a typical region of Loess Plateau. Potential evaporation equation of Holdridge was employed to calculate climatic aridity index (AI), and construct the regression model between Normalized Difference Vegetation Index (NDVI) and AI. Based on this model, we reversely deduced the potential vegetation index of Jinhe River Basin and proposed. a novel assessment method to quantify vegetation redundancy and deficiency (VRD). By this method, we found that the VRD indices for most watersheds of the northwestern basin were less than -0.2, displaying a severe vegetation deficiency. In the northern basin with atrocious natural conditions, the VRD indices ranged from -0.20 to -0.10, a relatively slight deficiency. However, in southeastern hilly of the basin, the indices were only between -0.10 and 0.10, the least deficiency. If analyzed in time series, vegetation deficiency generally occurred in high-vigor period from June to September. Farming vegetation had the largest deficiency, with the VRD index of -0.51 in July. Vegetation deficiency of sparse pasture was in the middle, with VRD index of -0.18 and that of forest vegetation was the least.