Four compounds were isolated from the lateral roots of Aconitum carmichaeli by Al2O3,silica gel and preparative HPLC.Their structures were identified as:(13R,15S,19S)-13,15,19-triol-hetisan (1),fuziline (2),neoline (3) and beiwutine (4),by methods of NMR,MS spectroscopy as well as single crystal X-ray crystallography.Among them,compound 1 was considered as a new diterpenoid alkaloid.