Abstract: The rcot and rhizoma of Rhaiiola fastigita S.H. Fu,s a traditional Tibetanmedicine used for promoting blcod circulation and relieving cough.In recent years,it was generallyused as a tonic.So, its chemical constituents were studied.A new flavonoid and six known compoundswere obtained.The known compounds were:4'-methoxyl herbacetin(I),rhodiolin(II),dihydrokaempferol(III),daucosterol(IV),tyrosyl(V)and salidroside(VI).The structure of thenew flavonoid was elucidated as herbacetin-8-O-α-D-lyxopyranoside(VII),by means of UV,IR,MS,¹H and ¹³C-NMR spectral data and chemical methods.