In order to promote the application of fractal theory in rill morphologic quantification, on the basis of reviewing the research on development process of fractal theory of soil erosion, the paper discussed a method of topographical data processing of slope erosion and hydrologic information extraction based on database DEM and ArcGIS software. Through the specific example, the method realized the calculation rill morphological fractal dimension by use of grid covering method. It got precise and efficient application effect.