Potassium 2-(1-hydroxypentyl)-benzoate (dl-PHPB), the pre-drug of 3-n-butylphthalide (dl-NBP), had the significantly therapeutic effect on the acute cerebral ischemia. The present study was to investigate the effect of dl-PHPB on the cognitive deficits induced by chronic cerebral hypoperfusion. Rats were orally administered three doses of dl-PHPB (13, 39 and 129mg/kg), dl-NBP 100mg/kg, and piracetam 600mg/kg daily for 21 days after the bilateral permanent occlusion of the common carotid arteries. The results showed that dl-PHPB, dl-NBP and piracetam significantly improved the spatial learning and memory deficits, and the effectiveness of dl-PHPB at dose of 39mg/kg was strongest. Meanwhile, the drugs decreased superoxide dismutase activity, reduced lipid peroxide and astrocyte activation in the cortex of the hypoperfused rats. Furthermore, dl-PHPB markedly reduced white matter rarefaction. The results indicated that preventing neuropathological alterations, inhibiting oxidative damage and inflammatory reaction might contribute to the improvement of dl-PHPB on hypoperfusion-induced cognitive deficits. Therefore, dl-PHPB has therapeutic potential for the treatment of dementia caused by decrease of cerebral blood flow.