利用TM和MSS卫星遥感数据提取反映生态环境的植被、土壤亮度、湿度、热度指数，结合气候数据和其它地学辅助信息，在GIS的支持下建立环境质量评价模型；利用该模型评价了内蒙古中西部地区19876、1987、1996年跨越20年的环境变化，从区域平均环境质量指数的变化和各级指数分布的区域面积变化两方面说明了研究区20年来的环境退化；分析了气候因子对环境质量变化的影响，定量说明了半干旱地区影响环境变化的气候因子主要是湿润度，指出20年来人为因素对环境质量的影响呈现越来越大的趋势。

The ecosystem of semi-arid region, the neighboring zone of agriculture and grazing area in Inner Mongolia is very sensitive and fragile. It is urgently demanded to assess the status of regional ecological environment quality degradation and o find out potential environmental degradation area.In this paper the vegetation, soil brightness, moisture and heat indices are extracted and evaluated from multi-band and multi-time TM and MSS remote sensing data to describe ecosystem status. An ecological environment quality evaluation model is built from these indices, climate data (air temperature, precipitation, evaporation and relative moisture) and other geographical auxiliary information (geomorphologic types, terrain elevation and land use information, etc.), on the support of GIS. The ecological environment change during 2 decades (from 1976,1987 to 1996)of middle and western Inner-Mongolia region is evaluated using this model. The ecological environment quality degradation of this region is analyzed from the aspects of average regional ecological environment quality index change, the area change of each ecological environment quality index, and from sample band analysis. Finally, this paper also analyzes the change of climate factors and the effect of these changes on ecological environment quality change quantitatively.Through correlation analysis of ecological environment quality change and climate factor change, this paper concludes that the climate changes are the major reason that leads to ecological environment degradation. By calculation of the correlation between ecological environment quality change and change of precipitation, evaporation and moisture, which is the combination of the former two factors, this paper puts forward that the major climate factor that affects ecological environment changes in semi-arid region is moisture. During the 20 years, the effect of human behavior increases a lot. Meanwhile this research also proves that the methodology used in this paper is effective.