Ligusticum Chuanxiong and its effective components were studied in the treatment of ischemic stroke, a common emergent disease in China. Some injections of the medicines, including Ligusticum, Ligustrazine, Ligustylid and ferulic acid, were tested clinically and experimentally. The results showed that the effects of the drugs were the same as or even better than those of the controls, such as papaverine, dextran and aspirin-persantin. They could improve brain microcirculation through inhibiting thrombus formation and platelet aggregation as well as blood viscosity.