Abstract: By applying Bayes principle，the comprehensive evaluation of eco-clim ate adaptability of crop and herbage was conducted in different&teas in northern ecotone．The analysis indicates that in semi-drought and drought areas，the eco-cli-mate adaptability of herbage is obviously better than that of crop and spring wheat．Thus an all-around identification of vegetations in northern ecotone is presented，which can be used as a reliable reference in further structure adjustment in these areas．