Abstract: Snow cover is an important component of the cryosphere and the study of snow cover trends is essential for understanding regional climate change and managing water resources. In this study,the spatio-temporal variations of snow covered area(SCA) and snow cover fraction(SCF) on the Tibet Autonomous Region(TAR) are analyzed based on the MODIS 8-day snow cover products(MOD10A2) from 2000 to 2014 using GIS spatial analysis techniques and relationships with main climate variables(temperature,precipitation) are discussed. Main results are as follows:(1) the averaged annual mean SCA on the TAR from 2001 to 2014 is 19. 0 × 10⁴km²,accounting for 15. 8% of the total area of TAR,and mean maximum SCA occurs in winter with covering 23% of the total area of TAR,followed by spring(22%) and autumn(16%),and mean SCA reaches a minimum in summer with 5% of total TAR area.(2) Over the last 15 years,there is a weak decreasing trend in annual mean SCA,in which a slight increasing trend in SCA exists in autumn and winter while a decreasing trend is found in other seasons with a significant decreasing trend in summer. There is a negative linear correlation between SCA and temperature whereas there is no certain relationship between SCA and precipitation.(3) The spatial differences of change trend of SCF on the TAR from 2000 to 2014 are large. The more obvious increasing trend of SCF exists in north part of TAR and southwestern Himalayas while more obvious decreasing trend of SCF mainly occurs in west and middle part of Nyainqentanglha mountains,eastern Himalayas with the most apparent decreasing trend in southeastern Naqu region. These spatial differences of SCF is dominated by snow cover changes in spring and autumn,and SCF overall is decreasing in spring and increasing in autumn over the last 15 years.(4) Likewise,the spatial differences of interannual variability of SCF on the TAR,dominated by snow cover variations in spring and autumn,also are large,and variability of SCF in autumn is greater than that in spring. General spatial distribution of interannual variability of SCF is similar with mean SCF of the TAR. More obvious variability of SCF is located at alpine interior,surrounding high mountains and their around regions. The smallest variability of SCF occurs in the middle and lower reaches of Yarlung Zangbo River valley,arid-warm valley of southeastern Tibet and middle and west part of North Tibet.(5) The regions with larger variability of SCF is main pastoral and snow disaster affected areas in the TP,which are key zone of snow cover monitoring and disaster prevention and mitigation.