To investigate the mutual influence and interaction mechanisms between the Tibetan Plateau and the West Qinling Mountains, this study selects Zhuoni County, Lintan County, and Tanchang County as representative areas of the combined zone between the two geographic units. Additionally, Maqu County, characterized by the geomorphological features of the Tibetan Plateau, and Cheng County in the West Qinling Mountains are chosen as control areas. Based on the quantitative construction of water and soil erosion sensitivity, ecological risk sensitivity, land desertification sensitivity, and biodiversity sensitivity, this study comprehensively evaluated the ecological sensitivity of five typical counties using the equal weight superposition method. Using spatial autocorrelation and geographic detector analysis, this study reveals the influence pattern and key influencing factors of the Tibetan Plateau on the ecological sensitivity of the West Qinling Mountains. The results show that: (1) As the distance between the counties and the Tibetan Plateau increases, the mean value of the comprehensive ecological sensitivity index shows an upward trend. The ecological sensitivity in the western side of the West Qinling Mountains, which is closer to the Tibetan Plateau, is relatively low, while the ecological sensitivity on the eastern side, which is farther away, is relatively higher. (2) The Tibetan Plateau landform, the combined zone of the Tibetan Plateau and the West Qinling Mountains, and the West Qinling Mountains landform represent counties with a relatively small percentage of extremely high sensitivity and high sensitivity areas, resulting in low ecological sensitivity and good ecological environmental conditions. (3) As the distance between the counties and the Tibetan Plateau increases, the global Moran's I for ecological sensitivity gradually rises, indicating a stronger spatial correlation of ecological sensitivity on the eastern side of the West Qinling Mountains. (4) The biodiversity of the Tibetan Plateau has a significant impact on the ecological sensitivity of the West Qinling Mountains, while the interaction between vegetation coverage and land use patterns serves as a core driving factor influencing the ecological environment of the West Qinling Mountains. Future research should continue to focus on the potential effects of vegetation coverage and land use changes on the ecological sensitivity of the West Qinling Mountains. This study provides an important foundation for analyzing the interactions between the two geographic units.