In this study, we conducted an integrative field investigation for the grassland community, productivity, and plant diversity in the Tibetan Plateau grasslands along a 1 700- km west- east transect. The properties of plant communities (e.g., aboveground biomass, belowground biomass, coverage, and density) and indices of plant diversity (e.g., richness index, Shannon- Wiener diversity index, and Pielou evenness index) showed longitudinal patterns along the west- east transect. All these indices increased significantly from the alpine desert, alpine meadow steppe, to alpine meadow in the Tibetan Plateau. Climatic factors (mean annual temperature (MAT) and mean annual precipitation (MAP) were the main factors controlling these longitudinal patterns, but their relative contributions to different parameters differed. MAT and MAP both controlled aboveground biomass, but the influence of MAP on plant richness was much higher than that of MAT. There was significant power- function relation between aboveground biomass and plant richness in the Tibetan Plateau grasslands(y = 0.219 7x0.754 9, R2=0.61, P<0.01). These findings provide insights into the response and feedback of Tibetan Plateau grasslands to the climate change in the future, and may help us to effectively protect the Tibetan Plateau grasslands and promote its sustainable development.