Real-time assessment of desertification sensitivity in the key ecological function area of grassland at the northern foot of Yin Mountain provides theoretical support for desertification control in China's arid and semi-arid regions, particularly in agro-pastoral transition zones. This research employs the MEDALUS model to create a comprehensive evaluation system for desertification sensitivity, incorporating factors like topography, soil, vegetation, climate, and hydrology. By dynamically monitoring desertification sensitivity in the key ecological function area of grassland at the northern foot of Yin Mountain and applying linear regression and geographical detectors, the study uncovers spatial-temporal variations in desertification sensitivity and its driving forces. The findings indicate that desertification sensitivity suppression is less effective in the northwest of the ecological zone than in the southeast While indices for topography, climate, and vegetation quality remained stable, the soil quality index increased from 1.028 to 1.165, signifying a reduced capacity of soil to mitigate desertification. Conversely, the hydrological quality index dropped from 0.769 to 0.713, indicating enhanced water resources' ability to suppress desertification. Over time, desertification sensitivity increased from east to west, with the non-sensitive area shrinking from 20.68% to 14.80%, and the extremely sensitive area expanding from 10.34% to 13.06%. Spatially, desertification sensitivity increased by 7.97% in areas surrounding the northwest deserts, grasslands around the northern slope of the Daqing Mountains, and grasslands adjacent to southeastern farmland. Meanwhile, desertification sensitivity dropped by 0.91% in desert-steppe regions extending from the Langshan Mountains northeast to the Ulanqab Plateau, resulting in a slight overall rise in sensitivity. Hydrological and climatic factors were identified as the main drivers of desertification evolution (q = 0.779, 0.768), while vegetation acted as a foundational factor (q = 0.757). The effects of topography and soil on desertification sensitivity were relatively minor (q = 0.286, 0.627). Grassland and forest areas increased by 317.02 km2 and 175.71 km2, respectively, while cropland and unused land decreased by 239.47 km2 and 527.85 km2. Although reforestation efforts have somewhat curbed desertification, the increase in desertification-sensitive areas in reforested zones (13.74%) was lower than in non-reforested zones (44.11%). Desertification sensitivity continues to rise overall, driven by improper reforestation practices, climate change, and water scarcity, necessitating further attention. This study provides a scientific basis for desertification control in arid and semi-arid regions.