It is discovered that the correlation between msavi ( modified soil adjusted vegetation index ) and vegetation coverage is higher than that between ndvi ( normalized differential vegetation index ) and grassland coverage when the land cover is low . so msavi can be used as the main index of grassland desertification degree . in order to evaluate the precision of the result, different methods such as supervised classification, unsupervised classification and visual interpretation on image are tried respectively 本文将其作为草地沙化的分级指标,直接通过计算分级,建立msavi等级与草地沙化程度的对应关系,确定草地沙化的程度,然后将msavl分类结果分别与目视解译、监督、非监督分类的结果进行了精度比较,其精度高于监督与非监督分类,与典型区现场绘制和目视解译结果的误差为5.9,能满足草地沙化监测实际应用要求。