A new alkaloid, named yunaoonitine wes isolated from the roots of Aconitum hemsleyamacm Pritz.var.circinatum W.T.Wang and A.geniculatum Flet.et Laue.var.unguzculatum W.T.Wang indigenous to Yunnan.The structure of yunaconitine was established as (I) through NMR, IR and UV spectrosoopies, and chemical degradations.