<p>Grasslands on the Qinghai-Tibet Plateau play a crucial role in carbon sequestration and livestock farming. However, carbon storage and the environmental effects of grazing in Qinghai-Tibet Plateau grasslands are not well understood. Here, we utilised the advanced Biome-Biogeochemical Cycles with Multi-layer Soil Module model to evaluate carbon storage and responses to grazing in Qinghai-Tibet Plateau grasslands between 1979 and 2018. The average annual vegetation carbon density and soil organic carbon density were found to be 46.07 ± 7.19 gC/m^² and 3,789.79 ± 17.08 gC/m^², respectively. Grazing resulted in the loss of 21.63 tg of vegetation carbon, while soil organic carbon loss was 108.83 tg in 2018. Grazing was found to have reduced both vegetation carbon density and soil organic carbon density in most grasslands of the Qinghai-Tibet Plateau. The study findings highlight the extent of carbon loss caused by unreasonable grazing practices.</p>