Ecological stoichiometry provides an important method for the determination of plant nutrient utilization and plant environmental adaptation strategies. Nitrogen (N) and phosphorus (P) stoichiometries play critical roles in the functions and structures of ecosystems by affecting important ecological processes. Studying the contributions of different functional groups to ecological stoichiometry could help to reveal the formation mechanisms of plant elements on a regional scale. Currently, most studies focus on comparison of ecological stoichiometry characteristics among different functional groups, but fail to discuss the variation in element contents among different plant functional groups with regard to geographic and climatic factors. The Qinghai-Tibet Plateau alpine region has a much higher elevation and lower temperature than the other regions in the same latitude. Thus, this region could provide ideal research conditions for investigating the relationship between plant element characteristics and variations in geographic and climatic factors. Using ecological stoichiometry theory, we analyzed the patterns of N and P contents among different functional groups (legumes, grasses, sedges and forbs) and how these varied with geographical factors (latitude and altitude) and climatic factors (mean annual precipitation and mean annual temperature) in the Qinghai-Tibet Plateau alpine region. We used these data to explore the formation mechanisms of plant N and P features in this region. The results showed that: 1) N and P contents were significantly higher in legumes and much lower in grasses, and that no obvious differences in N/P were found between the four groups. 2) As the latitude increased, the P contents of sedge folia decreased, while the N contents of forb folia increased. The P contents of all sample pool folia were found to decrease. As the altitude increased, the N contents of legume, grass, and forb folia decreased significantly, and the N contents of all plant folia also decreased. As the mean annual precipitation (MAP) increased, the N contents of sedge and forb folia, as well as that of all plant folia increased. As the mean annual temperature (MAT) increased, the N contents of sedge folia decreased, while their P contents increased. All plant folia element contents were found to have no correlation with MAT. 3) Folia N and P contents varied with latitude and MAP in sedges, and with altitude and MAT in legumes, grasses and forbs. These results are consistent with the patterns observed on a regional scale. These results indicate that the characteristics of element contents in different plant functional groups vary with geographic factors and climatic factors, and that plant species composition plays an important role in the regional-scale ecological stoichiometry. These results also show that the combination of different functional group plants can offset or cover up the characteristics of some groups, thereby affecting ecological stoichiometry on a regional scale.