Abstract: In the paper,taking Xiannangou watershed,representing the loess hilly geomorphology landscape,as the test area,a series of hydrologically corrected DEMs with grid cell from 5 m to 200 m were generated using ANUDEM based on the 1∶10 000 digital topographic map.Different resolution slope gradients were extracted within the Arc/Info slope calculation methods.By applying terrain analysis and geostatistical methods,changes of DEM-derived slope with horizontal resolution and their spatial distribution were systematically investigated,both on point,line and surface level.Research shows that with DEM resolution decreasing,slope at single point shows uncertainty,while points at the same slope level change regularly-low slope terrain increases at first and then decreases,middle slope terrain shows slight changes,and steep slope terrain decreases with logarithm greatly.