As part of our ongoing research program toward discovering structurally intriguing and biologically important diterpenoid alkaloids from the Aconitum genera, four new diterpenoid alkaloids, including three C-19-diterpenoid alkaloids (rockidines A similar to C) and one C-20-diterpenoid alkaloid (rockisine A) were isolated from the roots of Aconitum rockii Fletcher et Lauener in this paper. Their structures were elucidated on the basis of spectroscopic analyses (HR-ESI-MS, NMR and IR). All the new compounds 1 similar to 4, alone with ten known compounds 5 similar to 14 isolated in our previous work, were evaluated for their antifeedant activities, and compound 13 showed highly potent antifeedant activity with an effective concentration for 50% feeding reduction (EC50) at 0.13 mg/cm(2).