Abstract: Desertification is an extreme manifestation of ecological degradation which refers to land degradation in arid,semi-arid and dry sub-humid arid regions caused by various factors including climate variability and human activities.How to identify the desertification lands quickly and accurately is the key point to prevent and control deserts and desertification.This paper analyzes the changing trend,stability and desertification sensitivity of terrestrial ecosystem NPP in China from 2000 to 2015,and constructs a technical method to identify desertification lands.The main conclusions are as follows:(1) over the past 16 years,there have been different declining levels of net primary productivity in the south of Yin Mountain in Inner Mongolia,north of Tianshan Mountains in Xinjiang,and most regions in the south of Yangtze River,and vegetation ecosystem is in instability state in more than half of the regions;56.2% of the country's land belongs to the desertification sensitive area,and the above area is susceptible to desertification due to climate,natural conditions and human disturbance. (2) Since 2000,the area of desertification lands in China is about 207 400 square kilometers,accounting for 2.16% of the total land area.The area can be divided into five regions,namely the typical grassland and desertification steppe in the central Inner Mongolia Plateau,the Tianshan-Altay Mountain steppe area in Xinjiang,the temperate desert and oasis area in the lower reaches of the Tarim River in Xinjiang,the alpine-desert area of the Ali-Kunlun Mountains in the Qinghai-Tibet Plateau and south Qinghai alpine grassland area. (3) The desertification process is accompanied by the evolution of key parameters such as the decrease of productivity,the decrease of vegetation cover and the rising surface temperature.The formation of desertification is affected by climate,and the decrease of rainfall is the main factor that causes the process of desertification.In addition,human activities and unreasonable farming and animal husbandry also formed the desertification in some extended.

Key words: NPP, desertification, spatial distribution, ecological degeneration