Objective:To investigate the effects of Tiaoxin Recipe on the learning and memory ability of APP/PS1 transgenic AD mice and synapse and neuronal structure and synapse number in hippocampal CA1 region. MethodsFifty-four APP/PS1 double transgenic AD mice with three months old were randomly divided into the model group,Tiaoxin Recipe group and donepezil hydrochloride group,and 18 wild C57BL/6J mice with the same age and sex were taken as the normal group. Corresponding intervention were given in each group. After intragastric administration for 12 weeks,the behavioral test was performed by Morris water maze,and the synapse and neuronal structure and synapse number in hippocampal CA1 region were observed by transmission electron microscopy.  Results:①Compared with the normal group,the escape latency of mice in the model group was significantly prolonged (P<0.01),the number of platform crossing was significantly reduced (P<0.05),the stay time in the original platform quadrant was significantly decreased(P<0.01). The neuronal nuclear in hippocampus CA1 region showed pyknosis,the nuclear membrane was shrunk and thickened and the perinuclear empty halo was found. Some regions near the cell membrane were stained deeply,and there were heterochromatin and swelling mitochondria. The rough surfaced endoplasmic reticulum showed expansion as vesicle shape,the number of synapses in the neuropil was decreased significantly(P<0.01),and large axoplasmic vacuoles were found in synaptic structures. ②Compared with the model group,the escape latency of mice in the Tiaoxin Recipe group was significantly shortened (P<0.01),the number of platform crossing was significantly increased (P<0.01),the stay time in the original platform quadrant was significantly increased(P<0.05). The neuronal nucleus in hippocampus CA1 region were round with clear and complete nuclear membrane and obvious nucleolus. The chromatin was fine and smooth,the mitochondrial cristae was clearly visible and parts of mitochondria were slightly swollen. The rough surfaced endoplasmic reticulum and ribosomes were normal,the synapse structure was clear and the number of synapses was significantly increased (P<0.01),and the organelles lesion were alleviated.  Conclusion:Tiaoxin Recipe can improve the learning and memory ability of APP/PS1 transgenic AD mice,and improve the degeneration of neuron and synapse structure and reduction of synapses number,which shows protective effects on cognition and synapse.