To explore the mechanism of Deng Zhan Sheng Mai capsual treating vascular cognitive impairment(VCI), Modified Rankin Scale(mRS), Hamilton depression scale(HAMD), mini mental state examination(MMSE) as well as the indicator of P300 were used to evaluate the treatment. Methods:A total of 69 patients with Vascular Cognitive Impairment（VCI in neurology deepartment of Pudong New Area Hospital of Traditional Chinese Medicine from October 2010 to March 2014. All patients were assessed with Modified Rankin Scale(mRS), Hamilton depression scale(HAMD), and mini mental state examination(MMSE). And treatment emergent symptom scale (TESS) was adopted to evaluate the security. Oddball stimulus sequence P300 detection was taken, and superimposed target stimulation repeated for 200~500 times. The nanlysis time lasted for 1 000 ms. Results:After the treatment, two sets of data, mRS(2.121±1.139 and 3.273±1.008), HAMD(21.424±3.725 and 26.939±5.321) and MMSE(26.242±2.411and23.212±1.816), were significantly different(P<0.001). The incubtion period and amplitude of P300 in observation group improve markedly compaired with that of control group(P<0.001). Besides, there was no obvious adverees reaction in the treatment according to TESS, comparing the two groups, there was no statistically significant(P>0.05).Conclusion:The results suggest that the P300 can be the reliable evaluative means for vascular cognitive impairment and cognition disorder. In addition, DZSM is safe and effective in curing VCI.