Objective: To study the effects and mechanisms of “kai xing san” (KXS) on ability of learning and memory in mice. Methods: Passive avoidance performance (Step-down test) and water maze methods were used to evaluate the effects of KXS on ability of learning and memory in mice. Spectrophotometry was employed to determine acetylcholine esterase(AchE) and SOD activities in whole brain. Results: In water maze

mice with memory impairments induced by Scopolamine hydrobromide took longer latency to reach the end point

while KXS can reduce the latency. In step-down test

the right time (Ts) of the mice with memory disorders is shorter than that of the normal

while KXS can prolong Ts. KXS shows activities aganist the elevated AchE activity and the decreased SOD activity in whole brain of mice with memory disorders. Conclusion: KXS can improve the ability of learning and memory in models induced by Scopolamine Hydrobromide.