Abstract: To research the diversity of total activity of nitric oxide synthase（NOS） and effect of Xuesaitong on that diversity in limbic system with cerebral ischemia reperfusion injury of rabbits, and to study the protection of Xuesaitong on cerebral ischemia reperfusion injury of rabbits. Sixty three 3-month-old Harbin White rabbits ((1 500±150)g) were divided in 3 groups: the cerebral ischemia treatment group, the cerebral ischemia untreatment group and control group, randormly. The analog of cerebral ischemia were established by operation and the divisity of total activity of NOS and the effect of Xuesaitong on it were determined by the biochemistry technique.The results indicated that the total activity of NOS increased at 2 h after cerebral ischemia treatment reperfusion, increased to the highest at 6 h, and then decreased from 24 h to 96 h, and recovered to normal level at 120 h last. The cerebral ischemia treatment group showed bigger extent to descend, and recovered to normal level at 96 h. The cerebral ischemia treatment group and control group is obviously lower than that in cerebral ischemia untreatment group(P<0.01). The results suggested that Xuesaitong could protect the brain tissue with cerebral ischemia reperfusion injury of rabbits by decreasing the activity of NOS and maintaining the content of NO.