This study conducted computer-aided image analysis of land use and land cover in XilinRiver Basin, Inner Mongolia, using 4 sets of Landsat TM/ETM+ images acquired on July 31, 1987,August 11, 1991, September 27, 1997 and May 23, 2000, respectively. Primarily, 17 sub-class landcover types were recognized, including nine grassland types at community level: F. sibiricum steppe,S. baicalensis steppe, A. chinensis + forbs steppe, A. chinensis + bunchgrass steppe, A. chinensis +Ar. frigida steppe, S. grandis + A. chinensis steppe, S. grandis + bunchgrass steppe, S. krylavii steppe,Ar. frigida steppe and eight non-grassland types: active cropland, harvested cropland, urban area,wetland, desertified land, saline and alkaline land, cloud, water body + cloud shadow. To eliminatethe classification error existing among different sub-types of the same gross type, the 17 sub-classland cover types were grouped into five gross types: meadow grassland, temperate grassland, desertgrassland, cropland and non-grassland. The overall classification accuracy of the five land cover typeswas 81.0% for 1987, 81.7% for 1991, 80.1% for 1997 and 78.2% for 2000.