[Objective] To analyze the mechanisms of vegetation degradation and stability maintenance during the process of desertification at the southeastern edge of Mu Us sandy land

and to provide scientific basis for the repairing and controlling of desertification.[Methods] The methods of field investigation

field sampling

indoor assay and statistical analysis were integrated to analyze the change of vegetation characteristics during desertification in the study area.[Results] The results of functional and structural characteristics showed that the vegetation coverage

density

richness and Simpson diversity index reduced; The aboveground biomass increased first and then decreased. The changing regularity of organic matter was not obvious

while the total nitrogen content decreased and C/N increased. Vegetation characteristics changed suddenly in the mild desertification stage which was the key stage for desertification repairing. Furthermore

the quantitative measurement of vegetation stability showed that the stability index decreased in the process of desertification

stable and basically stable in non-desertification stage and potential desertification stage

unstable in other stages.[Conclusion] The vegetation degrades and the stability indexes decrease with desertification deepens. Therefore

maintain the virtuous circle of plant-soil system is the key of vegetation restoration and desertification control.