Abstract: The investigation on chemical constituents of Dendrobium nobile,which was used as a important Chinese traditional herbal medicine to treat nourishing body's essential fluid and reducing fever,promoting salivation reinforcing the stomach,nourishing the lung arrests cough.Four known natural products: dengibsin(1),2,4,7-thihydroxy-5-methoxy-9-fluorenone(2),chrysophanol(3) and β-sitosterol(4) ware obtained.Their structure were elucidated by spectral methods and comparied the physical data with those of compounds reported in the literature.