Detecting desertification by using remote sensing is an important task for China and other semi - arid and arid areas in the world. In this study, MODIS 1 km NDVI time series data of 2002 were used to classify land cover type in Xinjiang province and surrounding regions. During the classification, sparse areas, which are the areas at risk of desertification, are emphasized. A classification method, which is adapted to various land cover type and makes sparse vegetation emphasis, is introduced. This method better synthesizes seasonal influence factors and variable factors of natural conditions. Research results indicate that 0.24 million km^2 in Xinjiang and surrounding regions are potential desertification regions.