Objective: To study the effect of membranous milkvetch root on EAA in brain constitution after cerebral ischemical reperfusion injury. Methods: The cerebral ischemia model was established by carotid artery closure by clip. Then Glu, Asp, GABA, Gly in brain tissue were detected after 15 min of cerebral ischemia and 48h after reperfusion. Results: After 15min of ischemia, the Glu, Asp, GABA, Gly in brain constitution were obviously. Results: The Glu and Asp in brain constitution had improved obviously after 15 min ischemia( P <0.05, P <0.01), with the improvement of GABA( P <0.05).Membranous milkvetch root had decreased the Glu in brain constitution(P<0.05). After 48 cases of reperfusion, the Glu and Asp in brain constitution had improved obviously( P <0.05), with the decrease of the Glu in brain constitution( P <0.05)by the action of membranous milkvetch root. Conclusion: The mechanism of membranous milkvetch root anti ischemic cerebrovascular injury may had relationship to confrontation cerebral ischemia and increasing of EAA after reperfusion.