Abstract: Abstract Through applying the method of Franch--Swiss phytosociological school to study the vegetation types and using the method of fuzzy cluster analysis to class them, we have identified the vegetation of Yuanmou dry--hot river valley to be an "order" and name it "Dodonaeo--Heteropogonetalia contorti", two"alliances" and nine "associations" have also been identified and named based on the floristic criteria. All the character species of these types have been summarized and arranged into an "order--alliance--association table" to show a connect classification system. The vegetation of Yuanmou dry-hot river valley is somewhat like the "savanna" of tropics,it can be called "semi-natural savanna or secondary savanna".

Key words: Dry-hot river valley