Objective This study investigated the effects of salvianolic acid B (Sal B), a major bioactive component of the Chinese medicine salvia miltiorrhiza, on osteogenic differentiation of human periodontal ligament cells (hPDLCs).Methods Third passage PDLCs were used in this experiment. Methyl thiazolyl tetrazolium (MTT) method was employed to observe the effects of different Sal B concentrations on proliferation activity of hPDLCs. Alkaline phosphatase (ALP) activity and mineralization capability were measured, and mRNA expression of osteocalcin (OCN) was detected to investigate the effects of Sal B on osteogenesis of hPDLCs.Results Sal B did not influence the viability of hPDLCs. The ALP activity and OCN mRNA expression levels of hPDLCs were both significantly improved (P−1) compared with those in OIM group. Moreover, the number of mineralized nodules formed by hPDLCs were considerably higher under treatment with different Sal B concentrations (0.5, 1, and 5 μmol·L−1) than that in the OIM group.Conclusion Appropriate Sal B concentration can improve the osteogenic differentiation of hPDLCs.