There are serious land degradations caused by overgrazing in Qinghai-Tibet Plateau. Regional planning to preserve the plateau ecosystem is urgently needed. In this study, multi polynomial regression between EVI derived from MODIS satellite images and natural conditions for each pixel in time-series is taken at grazing land and conservation area. The result shows the response of EVI to land surface temperature and precipitation has a strong spatial auto correlation, and has significant relationships with elevation. The relationship expects the affection of grazing activities. In addition, the residuals are associated to the existence of grazing activities. This knowledge will be useful for mapping of grazing activities and the affection.