Abstract: The biome of Ordos Plateau was classified by using the Holdridge system of life zone. A computer model developed to determine ecotone provides a technological basis for studying the character of ecotone on Ordos Plateau. The location and width of the ecotone can be determined by the computer model on Ordos plateau. The simulated results coincide with the natural status. The biome of Ordos Plateau can be divided into steppe with Form. Stipa bungeana, desert shrub with Form. Caragana stenophylla or Artemisia frigida and desert with Form. Reaumuria soongorica,corresponding with traditional vegetation classification of vegetation that can be divided into steppe, desert-steppe and steppe-desert. The margin of steppe determined by traditional classification coincided with the results of the computer simulation, but the margin of desert shrub and desert biome determined by the computer simulation is different from the margin of desertsteppe and steppe-desert vegetation.