Based on Landsat 8-OLI (operational land imager) images and field surveys, we mapped soil salinization across seven ecosystems in the Manas River basin (MRB), and two models of soil salinization (namely an index model and a sensitivity model) were constructed on a regional scale and on the scale of a unit. ArcGIS ordinary Kriging interpolation was used to determine the spatial distribution of the sensitivity of each ecosystem to soil salinity. The ecosystems differed markedly in their sensitivity: the grassland ecosystem was the most sensitive and the farmland ecosystem was the least sensitive; the other five ecosystems, in descending order of their sensitivity, were desert, urban, forest, wetland, and shrubland. In terms of area, the ecosystems less sensitive to salinity accounted for 40% of the total area; those slightly sensitive accounted for approximately 24%; moderately sensitive, 12%; highly sensitive, 14.5%; and extremely sensitive, 9.5%. The extremely sensitive areas were mostly distributed around Lake Manas while the highly sensitive areas were mainly downwind of the lake. The moderately sensitive areas were occupied mainly by the wetlands and grasslands, the slightly sensitive areas by the deserts, and the least sensitive areas by the farmlands.