The Horqin Sandy Land， as a vital component of the “Three-North” Shelter Forest Project， necessitates specific and urgent research on desertification within the region. This study innovatively introduces the Analytic Hierarchy Process （AHP） to select and optimize indicators and factor variables from the original MEDALUS model， thereby enhancing the model and developing a new evaluation system for land desertification sensitivity. This system integrates indicators from five aspects： climate， soil， vegetation， land management， and socio-economic factors to assess the sensitivity of land desertification. Furthermore， the study employs the Geographic Detector （GD） model to explore the factors influencing the spatial differentiation of land desertification sensitivity in the Horqin Sandy Land. The findings reveal that： （1） Vegetation quality index has the highest weight in the index system for assessing land desertification sensitivity， with a weight coefficient as high as 0.4624， followed by the climate and soil quality indices. （2） Areas sensitive to desertification in the Horqin Sandy Land account for 78.22% of the study area， indicating a broad distribution of affected regions. Although the proportion of highly sensitive and extremely sensitive areas is relatively small （8.77%）， these areas are concentrated and severely desertified. （3） Single-factor analysis shows that soil texture has the most significant impact on the spatial differentiation of land desertification sensitivity， followed by soil moisture content. Interaction effects demonstrate that factors such as drought resistance， Net Primary Productivity （NPP）， temperature， soil moisture content， and soil texture significantly enhance their impact on the spatial differentiation of land desertification sensitivity when combined. The findings of this study can provide a scientific basis for formulating targeted and reliable priority desertification prevention plans and sustainable development models for the region.