How to simulate and reveal the spatiotemporal change scenarios of vertical distribution of vegetation ecosystem in Qinghai-Tibet Plateau under the future global climate change is very beneficial for quantitatively explicating the response of terrestrial ecosystem to climate change. In this study, the improved Holdridge Life Zone (iHLZ) ecosystem model was developed by combing the HLZ model and Digital Elevation Model (DEM) data. Based on the climate observation data in the T0 (1981-2010) period, and the Intergovernmental Panel on Climate Change Coupled Model Intercomparison Project (IPCC CMIP5) RCP2.6, RCP4.5, and RCP8.5 climate scenario data in the T1 (2011-2040), T2 (2041-2070), and T3 (2071-2100) periods, the vertical scenarios of vegetation ecosystem distributed in Qinghai-Tibet Plateau were simulated. The spatiotemporal shifting model of ecosystem mean center and ecological diversity index were introduced to explicitly analyze the change of vegetation ecosystem in different vertical zones of Qinghai-Tibet Plateau. The results show that there are 16 mountain vegetation ecosystem types in Qinghai-Tibet Plateau. The ice snow/ice, alpine moist tundra, and subalpine moist forest are the major vegetation ecosystem types and covers 56.26% of the total area of Qinghai-Tibet Plateau. -The sensitivity of alpine dry tundra, subalpine moist forest, mountain shrub, and desert to the climate change would be generally more than other types in Qinghai-Tibet Plateau under the three scenarios of RCP2.6, RCP4.5, and RCP8.5. The areas of alpine moist tundra, alpine dry tundra and desert show a decreasing trend, which will be decreased by 1.96×10⁴ km², 0.15×10⁴ km² and 1.58×10⁴ km² per decade between T0 and T3, respectively. The areas of subalpine moist forest, mountain moist forest and mountain shrub show an increasing trend, which will be increased by 3.42×10⁴ km², 2.98×10⁴ km² and 1.19×10⁴ km² per decade between T0 and T3, respectively. The mean center in the vegetation ecosystem has the largest shift distance under the scenario RCP8.5, followed by the scenario RCP4.5, and that has the least shift distance under the scenario RCP8.5. The ecological diversity of vegetation ecosystem will be reduced generally in Qinghai-Tibet Plateau in the future. In general, the greater climate change will lead to the larger impacts of climate change on ecosystem diversity, which shows an increasing trend from low altitude to high altitude in the Qinghai-Tibet Plateau.