This article introduces synthetically using RS, GIS and GPS (3S) technology to study ecosystem changes of Talimu river system within past 11 years. In this article, the data were analyzed by using GIS technology and the field sizes were investigated by using GPS instrument. A conclusion was concluded that in the past 11 years 1990 to 2000, in the region of the middle and lower reaches of Talimu river, the area of farmland had been increased 505,433km2, the area of nature/planted vegetation had been reduced 943,089km2, and the area of water body had been increased 80.477%. The area of desert in the middle and lower reaches of Tamilu river is increasing continually. The main reason is that the large number of nature vegetation was died, especially in the area of Huyang woods was declined. Finally, some suggestions were make to recover and father fragile ecosystem.