Impacts of biodiversity loss on ecosystem dynamics and functioning have aroused considerable attention and controversies. Loss of plant species is common in natural assembled community, whereas the response of ecosystem process remains unclearly. The continuous overgrazing of livestock has resulted significant plant species loss, like palatable grass and sedge species in alpine meadow on the Qinghai-Tibet plateau. In this study, we conducted a plant removal experiment to simulate the species loss along retrogressive succession gradient of alpine meadow resulting from long term overgrazing. A typical alpine meadow located on the eastern edge of the plateau was selected as the object to conduct the removal manipulation. The study site was fenced in April 2014 after the long term moderate winter grazing of yaks to exclude grazing of herbivores. Six removal treatments including: remove no plant species, remove Grass, remove Grass and Sedge, remove all species, randomly remove 25% of community aboveground biomass, and randomly remove 50% of community aboveground biomass. In middle July 2014 and 2015, we removed aboveground part of specific plant species individuals in 1 m×1 m plots. In late July 2016, the community coverage, height, species composition, diversity indices and biomass were investigated based on 0.5 m×0.5 m quadrats to detect response of alpine meadow to the removal experiment. The results showed that (1) removal of plant functional group (PFG) decreased the weighted-average height of community, but had no significant effect on the cumulative coverage of community. (2) Removal manipulation significantly influenced the summed dominance ratio (SDR) of Grass and Forb group, while no significant for Sedge group. (3) Removal of PFG increased the species evenness, and significantly influenced PFG diversity and dominance, whereas showed no significant effects for other diversity indices. (4) Removal of PFG reduced the litter biomass and Grass biomass. Only the removal of all plant reduced the community aboveground biomass. (5) In addition, further analysis showed that the community aboveground biomass was mainly depending on the Grass group, and decreased significantly with the increase of species evenness. And significantly competitive relationships were found among Grass, Sedge and Forb groups. The results showed that Grass species in the alpine meadow community have the greatest competitive advantage, the loss of plant species could change the community properties by means of influencing the inter-specific competitive relationships and significant plant biomass loss. The successive long-term monitoring on the response of community functioning to plant species loss should be strengthened.