Historical climate change affects significantly the current biogeography and the ongoing change will remain one of the major drivers of biodiversity patterns in the future. The impact of climate change on terrestrial ecosystems, especially on alpine vegetation,is of great importance in global change research. Situated in a closed basin surrounded by high mountains at an altitude of 4 500 m a. s. l.,the Altun Mountain Nature Reserve is currently the largest comprehensive nature reserve in China. The vegetation change will affect the habitats of wild animals including the poephagus mutus,Equus kiang and Pantholops hodgsonii in the nature reserve. Based on the values of SPOT-VGT NDVI vegetation index during the period of 1998-2008,the spatiotemporal variation of NDVI in the Altun Mountain Nature Reserve and its relationship with climatic factors including temperature and precipitation were studied. Using ArcGIS spatial analyst,the distribution of vegetation degeneration or improvement was lucubrated based on the linear regression analysis. The results showed that there was a distinct seasonal change of NDVI at the watershed scale,the DN value varied in a range from 33 to 53,it was rapidly increased in May,and its highest value occurred in September. The multi-year average value was about 40,it was decreased in 2001 and then increased. Spatially,the high values of NDVI occurred mainly in the Ayak Lake Basin,especially near the Kardun Checkpoint. Trend analysis using linear regression showed that the vegetation was holistically improved in the nature reserve except that near the rivers and lakes was degenerated to some extent. There was a significant linear correlation between the NDVI and the temperature and precipitation. A vegetation degeneration occurred in the marginal zone of the nature reserve possibly due to human activities.