The current year twigs of Rhododendron przewalskii were collected across three forest-grassland ecotones in the headwater region of Minjiang River in the southeastern Qinghai-Tibet Plateau. Along altitudinal gradients of their natural spatial distribution, stem length, stem thickness, and stem biomass of the twigs, as well as their relationships were measured and compared. Then, we compared total leaf mass and specific leaf area. Lastly, the relationships between stem and leaf traits and soil factors were evaluated by canonical correspondence analysis (CCA). The results show that except for Gonggangling, the soil factors of Doujitai and Kaka Mountains differed significantly between altitudes, and there were also significant differences in soil factors between different mountains at similar altitudes. Except that the high altitude specific leaf area of Kaka Mountain is significantly smaller than that of low altitude. Neither traits of stem (stem length, stem thickness, specific stem length and stem biomass) have no significant differences between altitudinal sites. Stem thickness, stem biomass, and specific stem length from similar altitudes also show no significant differences across sampling sites (P>0.05). However, the stem length at Gonggangling (3963 m) is significantly greater than that at Kaka Mountain (3921 m) (P<0.05). The relationships between stem length, stem thickness and stem biomass exhibit allometric growth, while stem length has an invariant allometric scaling relationship with stem thickness (SMA slope 2.8). The CCA results show that, carbon content, carbon to nitrogen ratio (C/N), soil organic carbon (SOC), total phosphorus (TP) and soil bulk density (SBD) were the main factors affecting stem and leaf traits. In general, small changes between different altitude gradients have little effect on stem and leaf traits of twigs, and soil environmental factors can be important reasons triggering the differences of the stem and leaf trait.