It is well known that a brief period of ischemia increases tolerance to a subsequent severe ischemic episode. In the present study, bilateral carotid arteries occlusion (BCAO) was applied as preconditioning to testify whether this kind of ischemia could preserve the function of mitochondria after the impairment induced by middle cerebral artery occlusion in brain. The activities of respiratory chain complex I to IV, mitochondria swelling, membrane potential, and membrane fluidity were observed. The activity of respiratory enzyme complex III、IV were most pronounced right after ischemic preconditioning (IP) compared with middle cerebral artery occlusion (MCAO) group. Mitochondrial swelling and membrane fluidity were protected by IP. Also membrane potential showed the increased trend. These results suggested that in mitochondria, energy metabolism was effectively protected due to this kind of preconditioning.