The source area of the Yangtze River in the northern Tanggula Mountains encompassed critical habitats of rare and endangered species. Its core zone was incorporated into the Sanjiangyuan National Park plan in 2021, becoming a key component of regional ecological security and biodiversity conservation. From June to November 2024, we conducted field investigations on wildlife resources in the Tangbei area of Sanjiangyuan National Park and surrounding regions using infrared cameras, line transects, and interview surveys. A total of 401 infrared camera sites were established, collecting 14417 independent images (out of 131908 images) over 21872 camera-days. A total of 12 line transects have been completed, with a total travel path of approximately 622km. The results showed that there existed 85 avian species from 13 orders, 26 families and 52 genus, and 30 mammalian species from 6 orders, 12 families and 26 genus. 13 species are listed as Class Ⅰ National Protected Wildlife and 22 species as class Ⅱ. 1 critically endangered (CR), 7 endangered (EN) and 8 vulnerable (VU) species were in China's Vertebrate Red List, and 13 species were endemic to China. We recorded three newly distributed species, which were Montifringilla nivalis, Phylloscopus fuscatus and Botaurus stellaris. The Palaearctic realm species was dominated (84 species, 73.0%), followed by Oriental realm (16 species, 13.9%), and wide spread species (15 species, 13.0%). Both mammals and birds were primarily represented by highland-type species (17 and 22 species). The G-F index was 0.75, indicating a high level of species diversity. The G-F index for birds was 0.85, higher than mammal (0.51). The Jaccard index showed that the species composition of Yanshiping and Gangni (Cj=0.776) was highly similar, while the similarity among other adjacent towns was moderate. Relative abundance index(RAI) demonstrated that the most prevalent mammal were Ochotona curzoniae, Lepus oiostolus, Vulpes ferrilata, Procapra picticaudata and Pseudois nayaur, and the most prevalent bird were Onychostruthus taczanowskii, Phoenicurus ochruros, Pyrgilauda ruficollis, Pseudopodoces humilis and Eremophila alpestris. The main factors influencing mammalian and avian diversity in the Tangbei region?were?found to be livestock grazing, road infrastructure, pasture fencing, and human-wildlife conflicts. For improved ecological conservation, it was proposed?to establish fixed monitoring transects in critical species habitats and migration corridors, along with seasonal monitoring networks for migratory bird sites, while enhancing systematic surveys of ground-nesting birds and small rodents. Additionally, the study recommended enhancing compensation for wildlife-inflicted damages by expanding coverage to include property losses (particularly housing damages), and establishing ecological corridors for migratory ungulates such as the Tibetan antelope whose traditional routes were fragmented by road infrastructure and grazing lands. Furthermore, linking conservation initiatives in Three-River-Source National Park with community welfare programs?was identified?as a strategy to ensure long-term biodiversity protection sustainability.