Abstract: OBJECTIVE：To approach the interrelationship between the regional cerebral blood flow （rCBF） and VEGF on CA1 of hippocampus and reveal the effect and possible mechanism of ischemic prostconditioning on rCBF and VEGF expression during focal cerebral thrombosis. METHODS: The thrombotic focal cerebral ischemia was induced by photochemical reaction in tree shrews, and ischemic postconditioning was established by clipped ipsilateral carotid of the animal at 4 hours after cerebral ischemia. The rCBF and VEGF expression in hippocampus CA1 area were detected, respectively, by laser-Doppler(LD) fowmeter and immunohistochemistry. RESULTS: The number of VEGF positive cells were increased markedly and VEGF expression enhanced after cerebral ischemic 4h,express of VEGF in 12h is the most intensification（P＜0.01）, the most attenuate in 72 h（P＞0.05）. The rCBF reduce along with temporal lasting in cerebral thrombus,especially decrease in 24h（2.55±0.28pu P＜0.01）;Then the rCBF also to a exten restoration,especially increase in 72h（18.74±1.59）.Postconditioning may gradually increase hippocampus rCBF, especially in 72h (10.42±3.75 PU ,P＜0.05) meanwhile the expression of VEGF is very high than that of ischemic except 8h （P＞0.05）,mostly in 12h（P＜0.01）; Electron microscope reveals that mitochondrium stress and endoplasmic reticulum cisterna formation of hippocampus were the most manifest in 24 h，but when we apply postconditioning on it ,the phenomenon can be relieived.CONCLUSION: The close relationship between rCBF reduction and VEGF expression in hippocampus CA1. Ischemic postconditioning may prolong “time window” of therapeutic cerebral ischemia, and the protection mechanism of ischemic postconditioning may associated with the increase of rCBF in 12h.Also ischemic postconditioning influence the rCBF of hippocampus maybe the key point of protective neuron .