Exploring the variation of leaf functional traits of plant community along environmental gradient can help us get a better understanding of the adaptive mechanism of the plant communities' response to environment. Altitudinal gradients could be used as powerful naturally formed experiments for testing ecological response of forest community to environment. Four typical types of forests along altitudinal gradients were investigated to analyze the variations of chlorophyll content, leaf dry mass content, leaf mass per area, leaf thickness, nitric concentration per unit area, nitric concentration per unit mass and their correlations in Mt. Shennongjia. Based on the analysis, we tried to reveal the adaptive mechanism of plant communities' response to environment. The results shown that leaf functional traits including LMA, N_mass and leaf thickness declined with the increase of altitude in the altitude ranging from 780m to 1970m. While LMA, N_mass and leaf thickness content of sub-alpine coniferous forest (2570 m) reached the maximum with 187.37g/cm², 1.92g/m² and 285.31μm, respectively. LMA of sub-alpine coniferous forests was twice as much as that of evergreen deciduous broad-leaved forests, 3.7 times as much as deciduous broad-leaved forests. N_mass declined with the increase of altitude (780-2570 m) except the N_mass of mixed evergreen and deciduous broad-leaved forests which was less than that of deciduous broad-leaved forests. The maximum chlorophyll content of sub-alpine coniferous forests (2570 m) and evergreen broad-leaved forests (780 m) were 48.84 and 44.12, and the maximum of LDMA were 454.93g/kg and 407.64g/kg for the same forests. Chlorophyll content and LDMA for Mixed evergreen and deciduous broad-leaved forests and deciduous broad-leaved forests in which the altitudes are between sub-alpine coniferous forests and evergreen broad-leaved forests had minimum chlorophyll content of 38.73 and 38.19, and LDMA of 338.93g/kg and 337.3g/kg. There existed significant correlation among the leaf functional traits. The results shown that there was significant positive correlation between leaf thickness and LMA/LDMC; leaf thickness positively correlated with LMA, while there was no significant correlation between leaf thickness and LDMC. Chlorophyll content significantly positively correlated with N_area while there was no significant correlation between chlorophyll content and N_mass. LMA significantly positively correlated with LDMC, N_area, leaf thickness and chlorophyll content; LDMC significantly positively correlated with N_area, chlorophyll content and leaf thickness; N_area significantly positively correlated with leaf thickness and chlorophyll content; leaf thickness significantly positively correlated with chlorophyll content. The results strongly demonstrated that single species' response to the environmental change could not reveal how the forests responsed to the environment. All species in a certain type of forests and their interaction of plant functional traits among species in the forests determined the mechanism of its response to environment with the environmental changes along altitudinal gradients.