<jats:title>Abstract</jats:title><jats:p>Three new C<jats:sub>20</jats:sub>‐diterpenoid alkaloids, along with twenty‐two known alkaloids, were isolated from the whole herbs of <jats:italic>Delphinium tatsienense.</jats:italic> The new alkaloids include a vakognavine‐type C<jats:sub>20</jats:sub>‐diterpenoid alkaloid, designated as tatsienenseine A (<jats:bold>1</jats:bold>), and two hetisine‐type C<jats:sub>20</jats:sub>‐diterpenoid alkaloids, designated as tatsienenseines B (<jats:bold>2</jats:bold>) and C (<jats:bold>3</jats:bold>). Their structures were elucidated by IR, HR‐ESI‐MS, 1D‐ and 2D‐NMR analyses.