Understanding the dynamic process of community diversity after grazing exclusion is crucial for the management and conservation of alpine grassland ecosystems. This study conducted a ten-year grazing exclusion experiment at four altitudinal gradients on Mount Gongga, ranging from 3000 m to 4130 m. Community diversity was surveyed at each altitude for the years 2012-2016, 2020, and 2022. We examined the changes in community diversity and species composition by mixed-effects model, principal coordinate analysis and triangular plots of β-diversity comparisons. Several key findings were revealed: 1) The mixed‐effects models showed that the interactions of altitude and time were significantly correlated with α-diversity, and the α-diversity at all altitudes shows a decline in the long-term grazing exclusion period, but the community composition at low altitudes changes at a slower pace compared to other altitudes; 2) Across all altitudinal sites, β-diversity patterns are similar initially and subsequently influenced by species replacement at 4130m with 7 new species appeared at 2022 compare to 2012, while at 3850 m, the richness difference is primary factor; 3) Species composition changes were more influenced by pioneer species (e.g., Potentilla leuconota and Plantago asiatica) at lower altitudes, whereas livestock-preferred species, such as those from the Cyperaceae and Poaceae families, played a crucial role at middle to high altitudes. These results illuminate the complexity of ecological replacement and how various factors, including altitude and grazing exclusion, influence the dynamics and composition of alpine grassland communities over time.