Oxidative stress and blood-brain barrier (BBB) disruption play important roles in cerebral ischemic pathogenesis and may represent targets for treatment. Earlier studies have shown that osthole, a main active constituent isolated from Cnidium monnieri (L.) Cusson, could be considered as an attractive therapeutic agent in the treatment of ischemic stroke. However, the mechanism underlying the protective effect remains vague. In this study we aimed to investigate the effect of osthole on transient cerebral ischemia as well as its mechanism(s) in C57 BL/6 J mice. Mice were subjected to transient global cerebral ischemia induced by bilateral common carotid artery occlusion for 25 min. Behavioral test was performed at 4 days after ischemia, followed by assessment of neuronal loss in hippocampal CA1 region. Osthole significantly improved the cognitive ability and enhanced the survival of pyramidal neurons in the CA1 region of mice after lesion. Further studies showed that osthole attenuated the permeation of BBB, which may contribute to antioxidative effect by increasing the superoxide dismutase activity and decreasing the malondialdehyde level in model mice. Further studies revealed that osthole obviously up-regulated the protein levels of nuclear factor erythroid 2-related factor 2/heme oxygenase 1 in HT22 cells. In conclusion, our findings indicated that osthole exerts neuroprotective effects against global cerebral ischemia injury by reducing oxidative stress injury and reserving the disruption of BBB, which may be attributed to elevating the protein levels of Nrf2 and HO-1.