The warming amplitude of the Qinghai-Tibet Plateau is significantly higher than that of other regions in the world, which has a profound impact on the structure and stability of the plant community in this region. In this paper, the open-top chamber (OTC) were used to study the effects of short-term warming on community structure and stability of three typical plant communities (alpine steppe, alpine meadow, and screes) in the vertical zone of the Nyainqentanglha Mountains in Tibet. The results showed that: (1)experimental warming changed the dominant species and affected the structural composition of the community, but had no significant effect on species diversity. (2) Warming significantly reduced the aboveground biomass (P < 0.05) and increased the belowground biomass (P < 0.01) in alpine meadows, leading to the change of biomass allocation strategies in the community. (3) Warming reduced the niche width of some species in the community, which in turn affected the community stability, with the alpine meadows changed greater (-66.8%) than the other two communities. These results can provide a scientific basis for alpine grassland ecosystems coping with and adapting to future climate change on the Qinghai-Tibet Plateau.