Abstract: Remote sensing images from 1990, 2000 and 2006 were classified with decision tree classification to examine the effect of the ecological water delivery project on the desertification changes in the lower reaches of the Tarim River.The results indicate that: the desertification speed slowed down, although the desertification progress is still continuing after the ecological water delivery project in 2000.The normal progress of desertification is from non-desertification to light desertification, then moderate desertification, then severe desertification, and finally extreme desertification.However, after the ecological water delivery project, desertification changes in the forward direction were reduced, while changes in the reverse direction were increased.The changed regions are concentrated on the borders of the oasis and on the both sides of the river.After the ecological water delivery project, the changed regions became much closer to the border of the oasis and both sides of the river.The relationship between desertification and distance to the river is closely related:the farther the distance, the more severe the desertification.The desertification is controlled within 1 km of the river sides, and the desertification direction was inversed after the ecological water delivery project.