Three new diterpene alkaloids, tangutidines A–C (1–3), and four known alkaloids (4–7) were isolated from the whole plant of Aconitum tanguticum, from which amphoteric diterpene alkaloids (1–3) were obtained for the first time. The structures of 1–3 were elucidated by detailed interpretation of spectroscopic data, including MS and NMR data. All of them were evaluated for their cytotoxic activities. Graphic Abstract: [Figure not available: see fulltext.]. © 2021, The Author(s).