Abstract: Aconitum gymnandrum maxim. (ranunculaceae) is used as an herbal medicine in Tibet area. A new diterpenoid alkaloid, gymnandine(Ⅰ) along with known alkaloids 14-acetyl-8-O-methyltalatisamine(Ⅱ), acoforine(Ⅲ), columbidine(Ⅳ), aconitine(Ⅴ), ranaconitine(Ⅵ), talatizidine (Ⅶ), isotalatizidine (Ⅷ), gymnanconitine (Ⅸ), talatisamine (Ⅹ), and atisine HCI (Ⅺ) have been isolated from this unique species. The structure of Ⅰ is determined on the basis of spectral evidences and comparison of the ¹³CNMR spectrum with that of denudatine. Ⅱ has not been previously reported as a natural product and Ⅲ～Ⅶ were isolated from this plant for the first time.