Working out a small watershed planning on the Loess Plateau needs many kinds of geographical data. By taking the Majiagou watershed in Ansai County,Shannxi Province as a typical experimental area,taking the DEM of the watershed as the basic data set,and using ArcGIS and various space analysis technologies,data mining experiments on slope graduation,landform classification,and aspect graduation are conducted and a series of data mining parameters and the indexes for drawing up the planning are obtained. Based on the multi-dimensional geography spatial data sets,a new method of data superimposition and fusion that takes the value code as the core are proposed. The research result has a certain reference value in the planning instruction for other small watersheds on the Loess Plateau.