<jats:p>C<jats:sub>19</jats:sub>‐diterpenoid alkaloids are the main components of <jats:italic>Aconitum duclouxii</jats:italic> Levl. The process of separation and purification of these compounds in previous studies was tedious and time consuming, requiring multiple chromatographic steps, thus resulted in low recovery and high cost. In the present work, five C<jats:sub>19</jats:sub>‐diterpenoid alkaloids, namely, benzoylaconine (<jats:bold>1</jats:bold>), <jats:italic>N‐</jats:italic>deethylaconitine (<jats:bold>2</jats:bold>), aconitine (<jats:bold>3</jats:bold>), deoxyaconitine (<jats:bold>4</jats:bold>), and ducloudine A (<jats:bold>5</jats:bold>), were efficiently prepared from <jats:italic>A. duclouxii</jats:italic> Levl (<jats:italic>Aconitum</jats:italic> L.) by ethyl acetate extraction followed with counter‐current chromatography. In the process of separation, the critical conditions of counter‐current chromatography were optimized. The two‐phase solvent system composed of <jats:italic>n</jats:italic>‐hexane/ethyl acetate/methanol/water/NH<jats:sub>3</jats:sub>·H<jats:sub>2</jats:sub>O (25%) (1:1:1:1:0.1, v/v) was selected and 148.2 mg of <jats:bold>1</jats:bold>, 24.1 mg of <jats:bold>2</jats:bold>, 250.6 mg of <jats:bold>3</jats:bold>, 73.9 mg of <jats:bold>4,</jats:bold> and 31.4 mg of <jats:bold>5</jats:bold> were obtained from 1 g total <jats:italic>Aconitum</jats:italic> alkaloids extract, respectively, in a single run within 4 h. Their purities were found to be 98.4, 97.2, 98.2, 96.8, and 96.6%, respectively, by ultra‐high performance liquid chromatography analysis. The presented separation and purification method was simple, fast, and efficient, and the obtained highly pure alkaloids are suitable for biochemical and toxicological investigation.