Leaf functional traits are influenced by both the external environment and their own evolution, thus, study on response of leaf functional traits and processes to environmental stress can address biodiversity and ecosystem functions loss under global change. In this study, the community weighted mean (CWM) values of leaf carbon, nitrogen and phosphorus content (LC, LN and LP) and dry matter mass (LDMC) were collected from 115 observed sites across alpine grasslands on the Qinghai-Tibet Plateau. Furthermore, precipitation, temperature, and soil factors were used to explore the response mechanisms of the leaf functional trait to habitat. The results showed that:(1) precipitation affected (P<0.01) on community leaf functional traits significantly, while temperature had non-significant effects (P>0.05) on them; (2) soil total nitrogen and soil organic carbon presented significant non-linear correlations with CWM_LC, CWM_LN, and CWM_LP (P<0.01), and linear correlations with CWM_LDMC; (3) soil water content had significant non-linear effects on CWM_LC, CWM_LN, CWM_LP and CWM_LDMC (P<0.05), and soil bulk density showed significant linear effects on these four functional traits (P<0.05). Our results highlighted that water was the major factor which governed the leaf functional traits of alpine grassland communities across the Qinghai-Tibet Plateau. Besides, alpine plants adapted to harsh environments via regulating leaf functional traits.