Abstract: Drawing the subcompartment boundary is an important step in establishing the subcompartmentbased forest resources inventory. It not only needs great ground work, but also is expensive and low efficient. This paper proposed a new method, the using contour of the relief map to extract the slope map. In order to use the slope map, the subcompartment boundary has to be drawn. During the extracting work, DEM and image processing were used via GIS technology. The results show that 70% of the extracted polygon lines can be superposed to the investigated subcompartment boundary.