Herein, we investigated the effects of different courses of electroacupuncture on learning and memory in mice with radiation-induced brain injury, and elucidated the underlying mechanisms. Sixty 4-week-old male C57/BL6J mice were randomly divided into the blank group, model group, electroacupuncture group 1 (7 d), electroacupuncture group 2 (14 d), electroacupuncture group 3 (21 d), and electroacupuncture group 4 (28 d). Except the blank group, all groups were irradiated with X-ray (8 Gy, 2 min) to construct the radioactive brain injury model. The electroacupuncture group was injected with "Baihui," "Fengfu," and bilateral "Shenshu" points, and the intervention was performed for 7, 14, 21 and 28 days according to the groups, respectively. After electroacupuncture, the Y-maze test was conducted to assess the learning and memory of mice in each group. Neuron morphology and synaptic ultrastructure in the hippocampal DG region were observed via Hematoxylin-eosin staining and transmission electron microscopy. Protein expression levels of the Notch signaling pathway components Notch 1, Hes 1, and ASCL 1 were detected via Western blotting. The results revealed that, compared to those in the blank group, the learning and memory function of mice decreased significantly in the model group (p<0.01). The number of neurons in the hippocampal dentategyrus (DG) region decreased and their arrangement was disordered. The number of synaptic vesicles in the presynaptic membrane decreased, the rate of synaptic interface decreased, the thickness of the postsynaptic density (PSD) decreased, and the synaptic cleft increased significantly (p<0.01). Compared to those of the model group, the learning and memory function of mice in electroacupuncture group was significantly improved (p<0.05, p<0.01). In the electroacupuncture group, the number of neurons in the DG region increased, with neurons neatly arranged. The rate of synaptic interface in the DG region improved significantly in all groups (p<0.01), the PSD thickness of mice in groups 2, 3, and 4 was significantly increased (p<0.01), and the synaptic cleft in groups 2, 3, and 4 was significantly decreased (p<0.01). Compared to the blank group, Notch 1 (p<0.05) and Hes 1 (p<0.01) protein expressions were significantly increased in the model group, while ASCL 1 protein expression was significantly decreased (p<0.01); compared those in the model group, the expressions of Notch 1 and Hes 1 proteins in electroacupuncture groups 2, 3, and 4 were significantly decreased (p<0.05, p<0.01), and the expression of ASCL 1 protein was significantly increased in electroacupuncture groups 3 and 4 (p<0.05 and p<0.01, respectively ). In conclusion, different courses of electroacupuncture can ameliorate the damage in learning and memory function caused by irradiation in mice, which is associated with improving the ultrastructure of synapses in the DG region and regulating the expression of related proteins of the Notch signaling pathway.