This study was purpose to investigate the B7-H3 expression in multiple myeloma cell lines and CD138 cells of patients with multiple myeloma, and explore its clinical significance. Three myeloma cell lines (RPMI8226, U266 and H929) were used. Forty-five patients with multiple myeloma were enrolled in the study. The expression of B7-H3 was detected by flow cytometry and RT-PCR. The relationship between B7-H3 and clinical prognostic factor was analyzed. The results showed that (1)In myeloma cell lines, high expression of B7-H3 was seen in RPMI8226 (92.30 ± 1.1)% and U266 (79.03 ± 1.2)% but not in H929 cell line (4.26 ± 0.2)%. (2) Exogenous IL-6 had no effect on upregulation of B7-H3 in myeloma cell lines. (3) In multiple myeloma patients, the proportions of B7-H3 positive cells in newly diagnosed, remission and relapsed patients were (48.58 ± 33.593)%, (22.16 ± 18.853)%, and (57.65 ± 28.296)%, respectively. The difference between the newly diagnosed and remission patients, and remission and relapsed patients was significant (P = 0.023, P = 0.004). (4)High B7-H3 expression was correlated with high numbers of bone destruction and high levels of serum calcium (P = 0.027, P = 0.046, respectively). It is concluded that the relation of B7-H3 molecule expression with prognosis of multiple myeloma may be negative, but with degree of bone destruction is positive, thus the high expression of B7-H3 may correlated with disease progression and bone destruction of patients with multiple myeloma.