To observe the effect of electroacupuncture(EA) at “Quchi(LI 11)” and “Zusanli(ST 36)” on the dyskinesia in middle cerebral artery occlusion(MCAO) rats based on synaptic plasticity.Methods:Sixty male SD rats were randomly divided into a sham operation group,a model group,an acupoint group,and a non-acupoint group,with 15 rats in each group.The MCAO model was induced in rats by the Zea-Longa method.EA treatment at “Quchi(LI 11)” and “Zusanli(ST 36)” was carried out for 14 days.The neurological deficits of rats were evaluated by the score of the Neurological Impairment Scale.The motor functions of rats in each group were compared by the CatWalk-assisted gait analysis system.TTC staining was used to observe the cerebral infarction volume.The ultrastructure and number of synapses were observed by transmission electron microscopy(TEM).The expression of synapse-related factors PSD-95 and synapsin in the ischemic motor cortex was detected by immunofluorescence assay.Results:After 14 days of intervention,compared with the model group,the acupoint group showed decreased neurological deficit score(P<0.05),quickened walking,shortened bipedal stance time(P<0.05),reduced cerebral infarction volume(P<0.05),improved synapse ultrastructure,increased number of synapses(P<0.05),and up-regulated expression of synapse-related factors synapsin and PSD-95(P<0.05).Catwalk gait parameters and cerebral infarction volume were consistent with synaptic ultrastructure improvement.Conclusion:EA at “Quchi(LI 11)” and “Zusanli(ST 36)” can improve dyskinesia in MCAO rats,and the mechanism may be related to the up-regulation of the expression of synaptic-related factors and the improvement of synaptic plasticity.