Abstract: Using the information of the meteorological observatory and the MODIS-NDVI data from 2000 to 2009 provided by NASA,this paper analyses the characteristics of NDVI's seasonal and annual changes in time and space in the last 10 years in this county.The results showed that the NDVI seasonal changes of Xinning County was in line with the biological characteristics of vegetation and the changes in phenology,which shows obviously seasonal pattern.There are also obvious differences in space. there were no obvious seasonal changes in the southeast and southwest areas with VI at a high state permanently.there were obvious seasonal variation in the central area with VI at a middle level. There were distinct seasonal changes in the northwest area with VI influenced by human factors.The vegetation cover in Xinning County is generally stable and improving.Shunhuang Mountain Nature Reserve and Wanfengshan Mountain Nature Reserve's vegetation cover has resumed in the last 10 years,but scattered vegetation degradation still exists because of the unreasonable exploitation in this county.

Key words: MODIS-NDVI, vegetation cover, Xinning County