Taking middle and upper reach of Yellow River drainage basin as research area,this paper divides it into three ecotopes and twenty-four ecosystem subregions by remote sensing information extraction,traditional information analysis and field investigations.The ecotopes include north-eastern Qinghai-Tibet plateau ecotope,Ordos plateau-Hetao plain ecotope and Loess Plateau ecotope.On the basis of ecotope partition,quantitative evaluation and analysis of ecological quality in middle and upper reach of Yellow River drainage basin was carried out by selecting environmental indices and mathematical modeling in Arcinfo system,quantitative evaluation of ecological quality in large areas was implemented.The research could provide scientific foundations for the Yellow River drainage area ecosystem environmental management.