Objective: To observe the therapeutic effect of Yangxue Qingnao granule (YXQNG) in treating chronic cerebrovascular insufficiency (CCI) and its possible mechanism.Methods: Eighty-three patients with CCI were randomly divided into YXQNG and nimodipine (ND) groups

the score of vertigo and the change in cerebral blood velocity before and after treatment were observed. And in the animal experiment

the authors adopted bilateral ligation of cervical carotid communis artery to establish CCI rat models in order to observe the effect of YXQNG and ND on incubation period of vertigo in rats and on memory performance.Results: After clinical treatment

the vertigo score of YXQNG group was 2.34

and that of the ND group was 4.18

the comparison between the two groups showed that the difference was significant (P< 0.05). After treatment

the middle cerebral artery mean velocity (MCA Vm) of YXQNG group was 64.78 cm/s

vertebral artery mean velocity (VA Vm) was 29.78 cm/s

while that of ND group was 60.34 cm/s and 23.23 cm/s respectively

the comparison between these two groups showing statistical significance and the difference being obvious (P<0.05). Experimental study showed that the rats in the model group after 12 weeks learning and memory were markedly lowered

the vertigo incubation period significantly lengthened

and compared with that of the model group

learning and memory of the YXQNG group was markedly improved and vertigo incubation period shortened

with the difference from that of the ND group insignificant

P >0.05.Conclusion: YXQNG could effectively improve CCI patients’ vertigo and other clinical symptoms and increase the cerebral blood flow

lessen the vertigo incubation of model group rats

elevate model group rats’ memory performance.