An updated checklist of bird species that occur in the Arjin Mountain Nature Reserve and its adjacent areas, including parts of Kunlun Mountain, Qimantagh and Kumkul Basin, is provided as part of the basic data for a second nation-wide field survey of wildlife resources of China (2010-2020). The information provided is based on field observations made from 2010 to 2017. A total of 172 bird species belonging to 95 genera of 42 families of 19 orders were identified as occurring in the reserve, accounting for 37.9% of the total bird species in Xinjiang Uyghur Autonomous Region. Among them, 85 species are migrants, 49 species resident, 33 species summer visitors and 5 species winter visitors. Six species of birds viz., Red-rumped Swallow (Cecropis daurica), Eastren Crowned Warbler (Phylloscopus coronatus), Blue-cheeked Bee-eater (Merops persicus), Robin Accentor (Prunella rubeculoides), Tibetan Rosefinch (Carpodacus roborowskii) and Japanese Sparrowhawk (Accipiter gularis) are being reported for the first time from Xinjiang. Among them, Blue-cheeked Bee-eater is reported from China for the first time.