The effect of ligustrazine on the expression of CD31 in syngenic bone marrow transplantation (BMT) mice was studied. Fifty-six Balb/c mice were divided into 3 groups: normal control group, BMT control group, and ligustrazine treated group. Syngenic BMT mouse models were established according to the literatures. In BMT control group and the ligustrazine treated group, the mice were given respectively orally 0.2 mL saline and 2 mg ligustrazine twice a day. On the 7th,14th, and 21st day after BMT, the mice were killed. The expression of CD31 on the surface of bone marrow nuclear cells (BMNC) was detected by flow cytometry. Peripheral blood leukocytes, platelets and BMNC were counted. Histological observation of bone marrow was made. The results showed that in ligustrazine treated group the peripheral blood leukocytes, platelets and BMNC counts, and the expression of CD31 on the day 7, 14, 21 after BMT were higher than in BMT control group (P＜0.01 or P＜0.05). In conclusion, ligustrazine could obviously enhance the CD31expression on the surface of BMNC after syngenic BMT in mice, which may be one of the mechanisms underlying the ligustrazine accelerating hematopoietic reconstitution in syngenic BMT.