Nine previously undescribed clerodane-type diterpenoids, jamesoniellides M-T and one ent-labdane-type diterpenoid, as well as one known analogue, were isolated from the Chinese liverwort Jamesoniella autumnalis (DC.) Stephani. Their structures were determined using MS, NMR spectroscopy, and electronic circular dichroism (ECD) calculations. Inhibition on LPS-induced NO production in RAW 264.7 murine macrophages was investigated, and the results showed that jamesoniellides Q-S exhibited moderate anti-inflammatory activity, with 50-80% maximum inhibition rate of NO production under the nontoxic tested concentration.