Rosmarinus officinalis contains diterpene phenols and diterpene quinones, such as carnosic acid and carnosol, exhibiting a wide range of biological activities. This paper reviews the latest papers about the diterpenoid compounds isolated from R. officinalis, and summaries the activities and mechanisms of them. It is found that 40 out of 62 diterpenoids in R. officinalis have anti-oxidant, anti-inflammatory, anti-tumor and neuroprotective effects. For them, the anti-oxidant involves the signaling pathway of Nrf2-HO-1/NQO-1, while the anti-inflammatory involves NF-κB, MAPK and Nrf2, the anti-tumor mechanisms involves Bcl-2, Akt/IKK/NF-κB and ATG, the neuroprotection involves PINK1/parkin and SIRT1/p66shc pathways. This will benefit to the full utilization of R. officinalis in the human health protection.