The community characteristics and productivity of alpine ecosystems are extremely sensitive to climate change in Qinghai-Tibet Plateau owing to harsh climatic environments. To explore the effects of warming on ecosystem productivity and their inter-annual differences in an alpine meadow, field experiments with temperature-gradient treatments (W1, W2, W3, and W4) using open top chambers (OTCs) were conducted in Tibetan Plateau. The results showed that the warming effect decreased the total coverage of the plant community (W1, W2, W3, and W4 significantly reduced plant community coverage by 28%, 23%, 59%, and 60% in 2015(P < 0.05), respectively; W4 significantly reduced plant community coverage by 83% in 2016(P < 0.05)) and the coverage of Kobresia pygmaea (W1, W2, W3, and W4 significantly reduced the coverage of K. pygmaea by 26%, 33%, 61%, and 64% in 2015(P < 0.05), respectively; W4 significantly reduced the coverage of K. pygmaea by 85% in 2016(P < 0.05)) compared with control treatment. The lower warming treatments (W1 and W2) had no significant effects on the coverage of Potentilla, whereas the higher warming treatments (W3 and W4) significantly reduced the coverage of Potentilla (W3, W4 significantly reduced the coverage of Potentilla by 58% and 60% in 2015(P < 0.05), respectively; W4 significantly reduced the coverage of Potentilla by 71% in 2016(P < 0.05). The warming treatments with a lower temperature range promoted growth and biomass accumulation of the community, whereas weakened the promotion effects or even inhibited growth and biomass accumulation when the temperature increased above a certain degree (W4 significantly reduced the aboveground biomass by 69% in 2015(P < 0.05); W4 significantly reduced the aboveground biomass by 82% in 2016(P < 0.05)). There were significant differences in the coverage of K. pygmaea and other species in the growth season between 2015 and 2016, but no significant changes were observed for Potentilla coverage. This study indicated that moderate warming is conducive for plant growth, but excessive warming can lead to declined grassland productivity and the deterioration of alpine meadows. Furthermore, Potentilla species from local communities are more resistant to global change, indicating their strong competitiveness in facing future climate warming.