The alpine timberline has been considered as a “monitor” of climatic change because of its sensitivity to climatic factors and non-stability in its structure. In this study, we investigated the eco-climatic characteristics at the alpine timberline of smith fir (Abies georgei var. smithii) in Tibetan Plateau using continuous data collected from micro-meteorological station. The results indicated that at the smith fir timberline in the Sergyemla Mountains, annual mean temperature and relative humidity were 1.3℃ and 79.4%, respectively. Annual precipitation was 892.6mm, most of which occurred between June and September. Mean temperatures for the warmest month and the coldest month were 9.4℃ and -6.4℃, respectively. The annual bio-temperature, warmth index and cold index were 3.1℃, 11.6℃.month and -55.9℃.month, respectively. The growing season length was 133 days, and the seasonal mean temperature was 7.7℃. The continentality index and moisture index were 34.0 and 217.5, respectively. The warmth index at smith fir timberline was close to that at the upper limits of Qilian savin (Sabina przewalskii) and Himalayan fir (Abies spectabilis). Moreover, the mean temperature for the warmest month, the annual bio-temperature, and the mean temperature for growing seasons at smith fir timberline were very close to the averaged values of alpine timberlines across china. The mean temperature for the warmest month at alpine timberline in Sergyemla Mountains, 9.4℃ was also close to the averaged value in the world (10℃). At the Sergyemla Mountains timberline, the mean soil temperature in 10cm depth during the growing season was 6.22℃, which was close to the averaged value ((6.7±0.8) ℃) in the world observed by Krner.