Abstract: From the stem of Acanthopanax obovatus Hoo., an endemic species collected from Huang-long county, Shaanxi Province, eight crystal constituents(Ⅰ-Ⅷ)have been isolated and the structure of the new natural compound Ⅷ were determined as n-butyl-α-D-mannopyranoside by spectroscopic data and chemical method. The known compounds Ⅰ-Ⅶ were identified as β-sitosterol, daucosterol, sesamine, dl-syrigaresinol, acanthoside D, stearic acid and laccerol on the basis of spectral evidence and comparison of authentic samples.