A RS database derived from Landsat MSS in middle 1970's, Landsat TM in 1990, Landsat ETM+ in 2000 and Landsat TM in 2005 was employed to analyze the desert sptio-temporal variation in source region of Yangtze River by GIS technique. The desert in study area was classified into six types: alpine desert, naked-rock desert, Gobi, sandy desert, bare land, and saline-alkaline land. Deserts cover the most area of source region of Yangtze River, occupying 28% of the total area. Alpine desert, naked-rock desert, Gobi, and sandy desert are dominant; bare land and saline-alkaline land are second. The evolution of desert developed positively from middle 1970's to 1990, with an increase by 43 935 hm², adversely from 1990 to 2000 with a decrease by 32 821.28 hm², again with an increase of 29 611.30 hm² from 2000 to 2005.