The aim of this study was to establish a model by single injection of Aβ_1-40+IA into rat brain basal ganglion and examine the effect of ZDY101, an active component of a Yin tonic from Chinese traditional medicinal herb. The results showed that the amnestic effect of co-injection of Aβ and IA lasted for at least 2 months. At same time, the total M-receptor density in model brain was significantly lower than blank control, indicating the change is profound enough for long term pathological studies or drug screening. It can be clearly seen that the decreased brain M-receptor density caused by Aβ was significantly increased by ZDY101. Such an elevation effect was significantly correlated with dose of ZDY101 when the dose was examined in a certain reasonable range. It can also be clearly seen that such an elevation of M-cholinergic receptor density was significantly correlated with the improvement of memory which indicated that the increase of M-cholinergic receptor density was an important factor in improving the memory of such animal model.