The relationship between plant and environment is one of key issues in the field of ecology. Plant functional traits and the responses of some traits to environment have been of interest to scholars since the 19th century. Studies on the changes in plant leaf and fine root traits and their correlation with elevation gradient explain how plants respond and adapt to a changing environment. Leaf length, width, thickness, area, specific leaf weight, chlorophyll content, root activity, fine roots (at a soil depth of 0-60 cm) characteristics, and other parameters of Abies georgei var. smithii at seven sites located at different elevations (3800, 3900, 4000, 4100, 4200, 4300, 4400 m) on Mt. Shergyla were measured and analyzed to understand the variation in leaf and root morphology along the elevation gradient and elucidate the response mechanism in plants growing at timberline in Southeastern Tibet. The results showed that: (1) Leaf thickness increased and leaf area, chlorophyll content, and root activity decreased with the increase in elevation. The optimal growth of A. georgei var. smithii was observed at the elevation of 3900 m. The leaf length, leaf width, and leaf area were significantly better than the other elevations. The greatest blade thickness was observed at 4200 m elevation. Leaf area and chlorophyll content decreased with elevation, but appear at the second peak at 4200 m.(2) Fine root biomass and fine root volume were the greatest for individuals growing at 3900 m and 4200 m, respectively. However, the two parameters were significantly lower in trees growing at 4400 m compared to the trees growing at other elevations. The fine root length density was relatively high at 3900, 4200, and 4300 m elevation; there was no significant difference in this parameter between trees growing at these three elevations, but the measured values were significantly higher compared to those calculated for trees at other elevations. The fine root length density was minimal for trees growing at 4400 m. The fine root surface area was significantly higher for trees growing at 3900 m compared to other elevations, followed by that observed in trees at 4200 m and 4300 m elevation. The fine root surface area was relatively small for trees growing at 3800, 4000, and 4400 m elevation. Specific root length reached the maximum at 4400 m. Root biomass and volume of A. georgei var. smithii measured at a soil depth of 0-60 cm and fine roots biomass and volume at a soil depth of 0-20 cm gradually decreased with the increase in soil thickness at each altitude. The fine root biomass and root volume were the highest for trees growing at 3900 m and 4200 m elevation. The root length density and root surface area had a significant increase at soil depths of 20-40 cm and 40-60 cm. As the soil depth increased, fine specific root length also increased, reaching the maximum at a soil depth of 40-60 cm. (3) Considering the characteristics of leaves and fine roots, the altitude of 3900 m is the optimal elevation for growth of A. georgei var. smithii. Timberline is located at 4200 m elevation, which indicates the zone of harsh environmental conditions and where Abies georgei var. smithii reaches its upper limit of distribution at the elevation of 4400 m in this region.