Cerebral edema after cerebral hemorrhage is one of the main reasons for aggravated disease, but the exact mechanism of cerebral edema has been yet completely clarified. The expression and significance of MMP-9 in rat brain after experimental Intracerebral Hemorrhage (ICH) were observed and analyzed. The male adult Wistar rats were randomly divided into three groups, the group with conventional hemorrhage was divided into 7 sub-groups (1 h, 3 h, 6 h, 24 h, 48 h, 72 h and 7 d) with 5 rats in each sub group according to different observation time; the group with different hemorrhage volume was divided into 4 sub-groups with 5 rats in each sub group according to different hemorrhage volume (25 μL, 50 μL, 75 μL and 100 μL); and the sham group (5 rats). The brain edema was observed by dry-wet method, MMP-9 expression was obtained by immunohistochemistry. The results showed that infiltration of inflammatory cells presented at 6 h in perihematoma after ICH, it reached maximum at 48 h, and continued to 7 d. MMP-9 positive cells began to increase at 1 h, it reached maximum at 48 h, and continued to 7 d. In the sham group, there was no hematoma and infiltration of inflammatory cells was found around hematoma, however there was little MMP-9 positive cells detected. In summary, there is the correlation in time period between MMP-9 expression in rat brain and brain edema after ICH. MMP-9 enhanced development of brain edema through degrading of the blood brain barrier component substances.