Objective：To observe the effect of Qingnao Tongluo prescription on synaptic structure in hippocampus of model rats with senile Alzheimer's disease(AD).Methods：Divided rats randomly into the young group，the aged group，the modelgroup，the huperzine A group and the Qingnao Tongluo prescription group.In addition to the young group and the aged group，the rats of other groups were established into models by injection of d-galactose and ibotenic acid into basal for ebrain.After the success of modeles tablishment，the Qingnao Tongluo prescription group was given 6 g/(kg·d)of Qingnao Tongluo prescription by gavage；the huperzine A group was given 0.3 g/(kg·d)of huperzine A，and the young group，the aged group and the model group were given the same volume of saline by gavage for four weeks continuously.Observed synaptic characteristics in area of CA1 and CA3 in the hippocampus of rats by electron microscope，and analyzed the synaptic numerical density(Nv)，surface density(Sv)and average size of synaptic conjunction in area of CA1 and CA3 in the hippocampus by stereological method.Results：No obvious change was found in the synaptic numerical density and surface density in area of CA1 and CA3 in the hippocampus of rats between the aged group and the young group.Compared with those in the aged group，the synaptic numerical density and surface density in area of CA1 and CA3 of rats in the model group were significantly decreased( P ＜0.01).Compared with those in the model group，the synaptic numerical density and surface density in area of CA1 and CA3 of rats in the Qingnao Tongluo prescription group significantly increased( P ＜0.05， P ＜0.01)；the synaptic numerical density in CA1 and CA3 and the synaptic surface density in CA3 area of rats in the huperzine A group were increased( P ＜0.01).Compared with that in the huperzine A group，the synaptic surface density in CA1 area of rats in the Qingnao Tongluo prescription group was increased( P ＜0.01).Conclusion：Qingnao Tongluo prescription has obvious improvement for synaptic density in hippocampus of rats with senile AD.