Eco-geological vulnerability assessment is a significant research topic within the field of eco-geology, but it remains poorly studied. The Mu Us Sandy Land, located in the central part of the farming-pastoral ecotone in northern China, plays a critical role in maintaining the ecological security pattern in this region. However, this sandy land also faces severe sandy desertification and ecological degradation. This study conducted a regional eco-geological vulnerability assessment of the Mu Us Sandy Land using a comprehensive index evaluation method based on eco-geological theories and survey results. To construct an appropriate index system for the eco-geological vulnerability assessment of the Mu Us Sandy Land, the study considered the sandy land's unique characteristics and identified 15 factors of five categories, namely geology, meteorology, soil, topography, and vegetation. The paper calculated the comprehensive weights of all the indices using the analytic hierarchy process (AHP) and the entropy weight method (EWM). Furthermore, it established the eco-geological vulnerability index (EGVI) and obtained the assessment results. The results showed that the eco-geological vulnerability of the Mu Us Sandy Land gradually intensifies from east to west, manifested as vulnerable eco-geological conditions overall. Specifically, extremely vulnerable zones are found in the northwestern and southeastern parts of the study area, highly vulnerable zones in the western and southern parts, moderately vulnerable zones in the central part, and slightly and potentially vulnerable zones in the eastern and southern parts. Areas with high spatial autocorrelations include the northern Uxin Banner- Otog Banner- Angsu Town area, the surrounding areas of Hongdunjie Town in the southeastern part of the study area, the Hongshiqiao Township- Xiaohaotu Township area, Otog Front Banner, and Bainijing Town, which should be prioritized in the ecological conservation and restoration. Additionally, the paper proposed suggestions for the ecological conservation and restoration of county-level administrative areas in the study area. Overall, the findings provide a valuable reference for the ecological conservation and restoration of the Mu Us Sandy Land and other desert areas in arid and semi-arid regions. (c) 2025 China Geology Editorial Office.