To estimate the effect of ligustrazine on the expression of PECAM-1/CD31 and hematopoietic reconstitution in syngenic bone marrow transplanted mice, 56 BALB/c mice were divided into 3 groups: normal control group, BMT control group, ligustrazine treated group (BMT + Ligustrazine) and syngenic BMT mouse models were established according to the literatures. The BMT control group and the ligustrazine treated group were given orally 0.2 ml saline and 2 mg ligustrazine twice a day respectively. On days 7, 14, 21 after BMT, mice were killed and peripheral blood cells, bone marrow nucleated cells (BMNC) were detected. Histological observation of bone marrow was made and the CD31 expression was assayed by flow cytometry. The results showed that in ligustrazine treated group the peripheral blood cell, BMNC counts on days 7, 14, 21 after BMT were higher than in the BMT control group (P < 0.01 or P < 0.05). The expression of CD31 in ligustrazine treated group on days 7, 14, 21 after BMT was also higher than in the BMT control group (P < 0.01 or P < 0.05). In conclusion, ligustrazine enhances CD31 expression in bone marrow cells after syngenic bone marrow transplantation of mice, which may be related to the mechanisms underlying the ligustrazine accelerating hematopoietic reconstitution in syngeneic bone marrow transplantation.