Abstract: Change of typical desert grassland in the northern Tianshan Mountains was analysed to give some constructive suggestions of sustainable development for both the environment and livestock. After the radiometric and geometric correction of TM/ETM+ remote sensing images in 1990, 1999, and 2008, the classification of land cover based on decision trees was implemented based on the vegetation index feature and vertical zone. The NDVI value calculated by radiometric corrected apparent reflectance was close to the actual surface features and generally showed the pattern: alpine meadow>farmland>temperate meadow>plain desert grass>piedmont desert grass. In the past 20 years, increasing farmland area occupied previous plain desert grassland and piedmont desert grassland to the extent that the new agricultural land area (296.3 km²) had become 1.54 times the total area of farmland in 1990. The trend of melting alpine ice transformed into alpine meadow became more apparent, and the reduced snow and ice area (74.7 km²) has reduced to 0.345 that in 1990.