Abstract: Seven flavonoids have been isolated from the methanol extract of the rhizome of Iris dichotoma Pall. (Iridaceae). Of the seven flavonoids, six had been isolated from other plants, they are irisflorentin(Ⅱ), wogonin(Ⅲ), rhamnazin(Ⅳ), irigenin(Ⅴ), tectorigenin(Ⅵ), tectoridin(Ⅶ). The first flavonoid is a new isoflavone, named dichotomitin, and was shown to be 53′-dihydroxy-4′5′-dimetheoxy-6,7-methylenedioxyisoflavone.