Abstract: Objective:To establish an animal model of Alzheimer's disease(AD) and to observe the therapeutic effect of tenuigenin(TEN) on deposition of β-amyloid protein(Aβ) and its neurotoxicity. Methods: A combined injection of aggregated Aβ1-40 and ibotenic acid(IBO) into the right nucleus basalis magnocellularis (NBM) was used to produce the AD rats model. The rats were divided into two group: model group and medicine group (made with feeding the model group with TEN for 30 days), the control group were injected with sterile normal saline in the same way as the above for the sham operation group . At 30 days after operation,The brain tissues were stained by HE staining, Nissl staining and cell ultrastructure were examined by electron microscope observation and deposition of Aβ in the NBM were examined by immunohistochemical technique. Results :The number of neurons in the model rats were less than the sham operation group, the deposition of Immunohistochemical study demonstrated that the injected Aβ1-40 in NBM was increased obviously and it is obvious that brown yellow macule deposition, the lipofuscin, increased obviously and the organelle such as mitochondria, RER and nuclear envelope were deformed in neuron. Conclusions: These results suggest that the aggregated Aβ1-40 deposition in the NBM related to the neuronal degeneration in the hippocampus which showed similar pathological characterizations of AD, tenuigenin can reduce the neuronal degeneration and the area of the remained Aβof AD rats and could protect neuron apoptosis caused by toxicity of Aβ.