Helan Mountain is the boundary between deserts and desert grasslands in China. Desert grasslands are distributed on the alluvial fan at its eastern foot， playing a positive role in maintaining ecosystem stability. Research is conducted on the spatiotemporal changes in fraction vegetation coverage （FVC）， and the main factors affecting vegetation coverage changes are analyzed. This study utilized Landsat satellite remote sensing data and inverted the vegetation coverage of desert grasslands in the alluvial fan area of the eastern foothills of Helan Mountains from 2001 to 2020 based on a pixel binary model. The spatial pattern and spatiotemporal variation characteristics were analyzed， and the driving factors were analyzed using Sen+Mann Kendall trend analysis， Hurst index， and parameter optimal geographic detector model. The results indicate that： （1） FVC shows a trend of "higher in the northwest and lower in the southeast" in space， mainly characterized by extremely low vegetation coverage and low vegetation coverage. The average annual FVC is 33.38%， and the overall vegetation coverage is at a relatively low level. （2） From 2001 to 2020， FVC showed a significant increase trend （P<0.01）， with an average annual growth rate of 0.25%. Overall， the northwest and southeast showed an improvement trend， with the improved area accounting for 93.24% of the total vegetation coverage area； The average coefficient of variation of vegetation coverage is 0.394， which is relatively stable overall. The eastern and central regions show the most drastic changes in space， with significant spatial differences. （3） The anti sustainability of vegetation coverage in the study area is strong， with an average Hurst index of 0.495， and 44.77% of the areas are greater than 0.5； From a spatial distribution perspective， the Hurst index is higher in the southern and western parts of the study area， indicating a higher sustainability of vegetation change， while the Hurst index is lower in the eastern and northern parts， indicating a lower sustainability of vegetation change. （4） The annual precipitation and land use type are the main factors affecting the spatial distribution of vegetation coverage in desert grasslands in the alluvial fan area of the eastern foothills of Helan Mountain. The interaction detection table shows that the impact of next year's precipitation on vegetation coverage is enhanced after the superposition of other factors， while the impact of topography and slope orientation on vegetation coverage is significantly enhanced； Risk detection indicates that each driving factor has an appropriate range of impacts on vegetation growth in the study area. This study helps to reveal the driving mechanisms of different factors on vegetation changes in desert grasslands in the alluvial fan area of the eastern foothills of Helan Mountains.