High accuracy DEMs is an important data in study of soil erosion and terrain feature space analysis.Taking Nanxiaohegou watershed in Gansu Province,which is in the gully region of Loess Plateau as an example,and 1∶10000 relief map as an data source,the method of high accuracy DEMs and extract soil erosion index of watershed are discussed.The result shows that the terrain feature information is better and truly based on high accuracy DEMs, it is contented in the build of digital watershed at present.