Some preparations of Man-Shan-Hong (Rhododerndron dauricum L.) leaves have beneficial effects in the treatment of bronchitis. For the exploration of the active principles, the present paper deals with the studies of the flavonoid components of this medicinal plant. Seven flavonoids were obtained by polyamide column chromatography or classical methods of separation. On the basis of spectroscopic analysis, preparation of derivatives, acid hydrolysis or enzyme hydrolysis and determination of physico-chemical constants, sis of them were identified as farrerol, 8-desmethyl-farrerol, hyperoside, kaempferol, quercetin and myrioetin. The seventh component was a new flavonol glycoside, its structure was established as queroetin-3-0-a-galacto-pyranoside and named isohyperoside.