A new diterpenoid alkaloid, 3α-hydroxy-12-epi-napelline (1), was isolated from the ethanol extract of the roots of Aconitum brunneum Hand-Mazz along with six known alkaloinds, i.e., 12-epi-napelline (2), liangshanine (3), 12-epi-dehydronapelline (4), songorine (5), aconitine (6) and benzoylaconine (7). The structure of the new compound was elucidated by spectroscopic methods.