This Study was designed to investigate the effects of Sibjeondaebo-tang (SDT) and Gamy-Sibjeondaebo-tang (GST, Sibjeondaebo-tang adding Cervi Pantotrichum Cornu) on the improvement in regional cerebral blood flow (rCBF) and mean arterial blood pressure (MABP) in normal rats, and in the rats with cerebral ischemia induced by middle cerebral artery occlusion, and further to determine the mechanisms. And, It was to investigate the effects of the SDT and GST with the change of histologic examination through the BDNF in the hippocampus CA1. In changes of cerebral hemodynamics, SDT and GST significantly increased rCBF in a dose-dependent manner but decreased MABP in normal rats. In mechanism of cerebral hemodynamics, Increase of GST-induced rCBF was significantly inhibited by pretreatment with methylene blue (0.01 mg/kg, i.p.), an inhibitor of guanylate cyclase, and Decrease of GST-induced MABP was significantly increased by pretreatment with methylene. These results suggested that the action of GST was mediated by guantlate cyclase pathway. In cerebral ischemics, the rCBF was stably improved by SDT (10 mg/kg, i.p.) significantly and stably increased by GST (10 mg/kg, i.p.) during the period of cerebral reperfusion, which contrast with the findings of rapid and marked increase in Control group. These results suggested that GST had anti-ischemic action in cerebral ischemic state. In histological examination through TTC stain, Sample A group and Sample B group decreased discoloration in the cortical part at $28^{th}$ day after MCAO induction. In immunohistochemistric response of BDNF, Sample A group and Sample B group increased respondent effect at $28^{th}$ day after MCAO induction. These results suggest that GST can Increase rCBF in normal state, as well as improve the stability of rCBF in cerebral ischemic state. Furthermore, methylene blue inhibitor study suggested the mechanism of blood flow enhancement by GST may be mediated by guanylate cyclase pathway.