Abstract: OBJECTIVE To evaluate the effect of Jiawei Kaixin San(JWKXS) on learning and memory abilities of multiple neuronal damage induced dementia mice and explore its mechanism. METHODS Dementia mice model was established via multiple neuronal damages， then the model mice were treated with water extracts， and water and ethanol combined extracts of JWKXS for 10d， while huperzine (0.05mg/kg) was applied as positive drug. The abilities of learning and memory were evaluated by behavioral tests， such as Morris water maze test and active avoidance test. In addition， cholinesterase(ChE) activities， superoxide dismutase(SOD) and protein expression levels of nerve growth factor(NGF) with its precursor in cerebral cortex of model mice were detected. RESULTS Behavioral tests showed JWKXS obviously shortened the incubation time of navigation and positioning， increased the times across platform and decreased swimming distances in Morris water maze test. In active avoidance test， the shuttle error numbers of model mice decreased with the treatment of JWKXS. In cerebral cortex， ChE activities were down-regulated while NGF levels were up-regulated. The effects of water and ethanol combined extract were better than the water extracts. CONCLUSION JWKXS can significantly improve the learning and memory ability of dementia mice induced by multiple neuronal damage. Its mechanism might be related to the inhibition of acetylcholine degradation and up-regulation of nerve factor expression.