Objective To observe the effects of Yuanzhi San (YZS) on the ethology and cerebral acetylcholinesterase(AchE) activity of mouse model of memory disorder induced by scopolamine. Methods Sixty mice were randomly divided into six groups, namely blank control group, model group, positive medicine group, and low-dose, middle-dose and high-dose YZS groups. Except for the blank control group and model group were given the normal saline, the mice in other groups were administered with the corresponding drugs for 10 days. And then, mice in the medication groups were given subcutaneous injection of scopolamine in the dose of 3mg/kg to induce memory disorder model. Morris water maze test and step-down test were adopted for the observation of the learning-memory ability of the mice, and at the end of the tests, the activity of AchE in mouse cerebral cortex was measured by a biochemical method. Results Compared with the model group, escape latency was decreased, and retention time and swimming distance in the effective area in Morris water maze test were prolonged in YZS groups (P<0.05); latency in step-down test was also prolonged (P<0.05). YZS had an effect on decreasing AchE activity in the cerebral cortex of model mice (P < 0.05 compared with the model group). However, the differences were insignificant among the medication groups(P>0.05). Conclusion YZS exerts certain effect on improving learning-memory ability of memory disorder mice induced by scopolamine , and the mechanism might be related with the inhibition of AchE activity in the cerebral cortex of model mice.