Objective: To explore the underlying mechanism by which acupuncture regulates the peripheral leukocyte count and observe the relationship between the effects of electroacupuncture (EA) and the spleen ultrastructure in leukopenia. Methods: Leukopenia models of rabbits were established by injecting cyclophosphamide (CY) into rabbits' ear vein,and then the rabbits were treated with acupuncture. The peripheral leukocyte count and classification were measured daily. At last, after the animals were anesthesized, the abdominal cavity was opened, and a piece of spleen tissue was cut. The diameter of splenic sinusoid basal lamina eyehole was measured under electric microscope. Results: The peripheral blood leukocyte count in the EA group increased significantly with shift to right of the granulocyte nuclei compared with model control group (P＜0.01). Moreover, the calibers of splenic sinusoid basal lamina eyehole in the EA group were larger than those in the model control group (P＜0.05). Conclusion: Acupuncture can enhance the peripheral leukocyte count by promoting spleen activity in the early phase of leukopenia.