| Since 1980s, glacier retreating, permafrost degradation, lakes shrinking, vegetation degradation and so on happen in the regions. There is very important scientific meaning to study the changes of evapotranspiration and water conservation.Using the surface energy balance system, we calculate the annual evapotranspiration from 1991 to 2001. Employing linear regression method we count the evapotranspiration trends in every pixel. The method of Geographic Information System being used, the main impacts such as temperature, surface land temperature, precipitation and NDVI (vegetation index) how to impact evapotranspiration variability has been assessed. Using factor analysis, we find out the main factors affecting the source ecological. The introduction of the concept of evaporation than to find out the way of the source of ecological changes.The results show that evapotraspiration has been increasing at the speed of 68.0mm/10a. There are 20 to 30 years, 6 to 13 years, 2 to 5 years of 3-scale cycles. Evapotranspiration annual changes is mainly affected by annual temperature change. In the southeast of the region with large rainfall and relatively dense vegetation, evapotranspiration is large, in the northwest of the region with small rainfall and sparse vegetation, evapotranspiration is much less.Environment influence factors such as slope, rainfall, elevation, aspect, evapotranspiration, surface temperature can be represented by two main factors.The supply and the redistribution of water are two factors of Eco-environmental changes. In the southeastern of region, water source conservation is adequately, northwest is scarce. Water conservation volume been affected by aspect and slope factors. Evaporation than mainly in the 1 ~ 4. Evaporation ratio is relatively small from 4～9 than others. The trend of Evaporation ratio is upward except may and october. The change trend in the southeastern of region is bigger than the change trend in the northwest. Overall, the regions rends to dry.
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