Abstract: The respective data of TM, ETM+ and ASTER in1999, 2002 and 2004 and together with the basic geographic data in the Lower Reaches of Tarim River were monitored, collected and analyzed in qualitative and quantitative way before and after the emergent water project in the Lower Reaches of Tarim River. Classifying the desertification land, modeling the target information extraction and establishing the dynamic change patterns, the spatial-temporal changing trend of desertification land in the study area showed that the none and weak desertification area increased from 14 768.33, 153 261.03 hm2 in 1999 to 19 994.23, 159 953.76 hm2 in 2004, respectively. The moderate desertification area decreased by 2 981.58 hm2 on average annual, and the severe desertification area went up only by 1.07 hm2. During the period of research, some desertification lands were evidently reversed and in turn the continuing trend of land degeneration was partly stopped and alleviated. The ecological environment far away from the river bed, however, was still bad and severe, and the entire ecological environment of the river basin was less optimistic because of the limited water inflow coming from the emergency water project as well as the linear water delivery.