The quantitative evaluation on effect of spatial scale on soil and water loss is the key issue of“scale, pattern and process”of soil and water loss because soil and water loss is the representative process with variability in multi-scale. The sediment of Wu-qiao-he watershed was estimated in three spatial scales based on high resolution digital elevation model and GEOWEPP in this paper. Results showed that there were obvious discrepancy on the characteristics of watershed soil and water loss in different spatial scales. The total sediment per year decreased from 3.79 10⁵ t to 1.25 10⁵ t and 0.84×10⁵ t the sediment of unit area per year decreased from 33.09 t hm^-2 to 10.94 t hm^-2 and 7.29 t hm^-2 and the ratio of carrying sediment decreased from 1.000 to 0.331 and 0.220 when the spatial scales varied from slope to sub-watershed and watershed. The sediment of watershed outlet could be known and at the same time, the intensity and spatial distributing of soil erosion could be described based on GIS and GEOWEPP and the measures of soil and water conservation could be rather disposed.