OBJECTIVE: To explore the mechanism of Baisuifang Granule in treating cognitive malfunction after cerebral infarction. METHODS: One hundred and sixty patients with cerebral infarction were divided randomly into two groups. Eighty patients were treated with Baisuifang Granule and 80 with nimodipine for two months. Clinical observation and laboratory examinations were performed for Mini-Mental State Examination (MMSE), clinical symptoms, Chinese Stroke Scale (CSS), hemorrheological indexes and fibrinogen before and after the treatment. RESULTS: Baisuifang Granule could improve MMSE, reduce the scores of clinical symptoms and CSS, and meliorate the blood rheology. The total effective rate for clinical symptoms in the Baisuifang treated group accounted to 76.25%, with statistical difference comparing to 58.75% of nimodipine treated group (P<0.05). There was significant difference in symptom integral, CSS and whole blood viscosity at the high shear rate, respectively (P<0.01). CONCLUSION: Baisuifang Granule is an effective Chinese medicine for treating cognitive malfunction after cerebral infarction.