Objective We modeled superior vena cava (SVC) occlusion in rabbits to observe the effect of different blocking time on brains. Method Forty rabbits were randomly divided into four groups. Group Ⅰ was set as a control group (n=10). Group Ⅱ was set as a 30 minutes SVC blocking time group (n=10). Group Ⅲ was set as a 60 minutes SVC blocking time group (n=10). And group Ⅳ was set as a 90 minutes SVC blocking time group (n=10). We detected the patho- logical and physiological changes in the course of the experiment. After the intervention, malondialdehyde (MDA) and superoxide dismutase (SOD) of brain tissue homogenate in each group were detected. Brain sections were stained with hematoxylin-eosin (HE). And we observed the edema and damage of brain tissue under the microscope. Results There was no obvious change on the content of MDA and SOD within 30 minutes interruption (P>0.05). When the blocking time was longer than 60 minutes, the content of MDA increased significantly (P<0.05) and the SOD decreased significantly (P<0.05). Compared to the group Ⅰ and the group Ⅱ, the brain water content in the group Ⅲ and the group Ⅳ with a interruption time above 60 minutes increased significantly. And under the microscope, the cell edema and damage induced by ischemia and hypoxia increased significantly. Conclusion The blocking time of SVC within 30 minutes is relatively safe. But there would be significant brain edema and neurocyte degeneration when the blocking time is more than 60 minutes.