A method has been developed for rapid analysis of the stem bark of Acanthopanax giraldii Harms (A.G) by HPLC/DAD/ESI/MS2. The separation was performed on Zorbax SB-C-18 (250 x 4.6 mm, 5 mu m) column with gradient elution of acetonitrile water as mobile phase. The mass spectral analysis was carried out on the Agilent 1100 series ion trap mass spectrometer with an electrospray ionization interface in negative ion mode. Uridine, Guanosine, Adenosine, Liriodendrin, Protocatechuic acid, Syringin, Chlorogenic acid, Caffeic acid were identified in the stem bark of A.G by the comparison of the HPLC retention time, UV spectra, and the mass spectra with corresponding authentic samples using the LC/DAD/ESI/MS2 technique; the last 4 components identified in the A.G have not been reported to date.