Abstract:The study, using combination of sample lines and plots, carried out field investigation and sampling analysis of plant community at different altitudes in the Motianling northern slope Dayazi of Gansu Baishuijiang National Nature Reserve. Using linear regression analysis, Pearson correlation analysis and curve fitting analysis method, the study researched on specific leaf area (SLA), leaf dry matter content (LDMC), leaf carbon, nitrogen and phosphorus contents (LCC, LNC, LPC) and stoichiometric (C/N, C/P, N/P) change characteristic of woody plants. Besides, variation trend and correlation of leaf traits at species and community levels with elevation gradient. The results showed that: (1) at deciduous broadleaved forest belts on the Motianling northern slope Dayazi, there are 23 species of woody plants belonging to 13 families, including 6 trees and 17 shrubs. Among them, the species of shrubs are superfluous trees. In addition, a few species are distributed at different altitudes, such as Larix principisrupprechtii and Lespedeza bicolor, which reflect the adaptation of different plants to heterogeneous environments. (2) The coefficient of variation of leaf functional traits in the smallest is LCC (4.6%), SLA is the biggest (42.1%), of which only LCC variation is weak, and the other leaf traits belong to moderate variation. These show that the woody plant carbon gain is maintained at a certain level based on synergy in other leaf traits to ensure the stability of the community. (3) Correlation between leaf functional traits is widespread, which is a strategy of plant adaptation to environment. The study shows that the correlations between SLALNC and LNCLPC are the same in species and community levels and the degree of correlation, and the correlation between other leaf traits are different, which provides a certain basis on selection of traits for future research. (4) The trend of leaf functional traits varied with altitude: apart from the variation trend of C/N and N/P at two levels, the other traits show basically the same trend with altitude at the species and community levels, but the significant degree of LNC was the same, the others were different. This phenomena reflects the adaptation of different leaf functional traits of woody plants to different environments at altitudes.