The present paper approached to mechanisms of Bu Shen Huo Xue Fang preventing and treating vascular dementia （VD） in mice. The effects of Bu Shen Huo Xue Fang on study and memory ability

and NMDA receptor and activity of nitric oxide synthase （NOS） in hippocampus were observed in VD mice. Results prove that Bu Shen Huo Xue Fang can markedly shorten the time of the mice of VD looking out the plantform in Morris’water maze

improve study and memory ability

inhibit NMDA receptor in hippocampus and increase NOS activity

antagonize excitatory toxicity and neuron injury induced by NO

so as to protect neurons from damage.