Abstract: The proposed construction area of the Selincuo-Puruogangri National Park (Se-Pu National Park) is endowed with the most abundant rare and endangered species in the alpine grassland ecosystem, and is the centralized distribution area of lots of high-quality natural landscapes and cultural heritages. The local fragile eco-environment is the primary issue that should be considered during the establishment of the Selincuo-Puruogangri National Park. Based on the research scheme of “factor identification, index construction, single factor assessment, integrated assessment”, we evaluated single-factor sensitivity of freeze-thaw erosion, soil erosion, land desertification, soil wind erosion, and habitat environment respectively, after identifying eco-environment vulnerability factors. Combined with the limiting factors of elevation, slope and important ecosystems, comprehensive assessments of the eco-environment vulnerability of the study area were conducted to provide scientific basis for the delineation of spatial extent, the function division of national park, and moderate development of eco-tourism. The results showed that: (1) There are serious eco-environmental problems, including freeze-thaw erosion, soil erosion, grassland degradation and biodiversity loss in this area. (2) From the perspective of different single factor sensitivity, the area mainly had moderate and high sensitivity of habitat environment, moderate sensitivity of soil erosion, mild and moderate sensitivity of freezethaw erosion, insensitivity and mild sensitivity of soil wind erosion. (3) The comprehensive assessment showed that the eco-environment of the study area is highly fragile, with a proportion of 57.60% of highly vulnerable areas, mainly distributed in the west and north parts. The lowly vulnerable areasaccount for 7.38% of the total area, mainly distributed in the eastern region. Nima County has the smallest distribution area of low vulnerability, while Anduo County has the most. The area with high vulnerability is widely distributed in Shuanghu County. (4) It is suggested that the future human activities and tourism development should be mainly allocated in low vulnerable areas in the national park. Meanwhile, the protection of ecosystem integrity and authenticity in the highly vulnerable areas should be strengthened.