<jats:title>Abstract</jats:title><jats:p>Four new C<jats:sub>19</jats:sub>‐nor‐diterpenoid alkaloids, named brachyaconitines A–D (<jats:bold>1</jats:bold>–<jats:bold>4</jats:bold>), were isolated from the roots of <jats:italic>Aconitum brachypodum</jats:italic> <jats:sc>Diels.</jats:sc> Their structures were elucidated as 3‐<jats:italic>O</jats:italic>‐acetyl‐20‐deethyl‐20‐formylaconitine (<jats:bold>1</jats:bold>), 3‐<jats:italic>O</jats:italic>‐acetyl‐19,20‐didehydro‐20‐deethylaconitine (<jats:bold>2</jats:bold>), 3‐<jats:italic>O</jats:italic>‐acetyl‐8‐de(acetyloxy)‐7,8,17,20‐tetradehydro‐20‐deethyl‐7,17‐secoaconitine (<jats:bold>3</jats:bold>), and 1‐<jats:italic>O</jats:italic>‐methylflavaconitine (<jats:bold>4</jats:bold>) by means of MS, IR, 1D‐ and 2D‐NMR analyses. The structure of compound <jats:bold>1</jats:bold> was confirmed by an X‐ray diffraction experiment.