Abstract: Objective：To observe the effects of Penicillin-Streptomycin on the proliferation, odonto-and osteogenic differentiation and the expression of the inflammatory cytokines of inflamed human dental pulp stem cells (iDPSCs) in vitro. Methods：iDPSCs were isolated from inflamed human dental pulp and cultured respectively in alpha minimum essential medium(α-MEM) or containing 100U/ml Penicillin-Streptomycin. The proliferation ability of iDPSCs was evaluated by MTT colorimetric assay. Alkaline phosphotase (ALP) activity, real-time RT-PCR and Western blot were used to examine the odonto/osteogenic potential-the the expression of RUNX2/RUNX2,DSP/DSPP,OCN/OCN and the expression of TNF-α of iDPSCs. Results：MTT assay showed that 100U/ml Penicillin-Streptomycin had no effect on the proliferation of iDPSCs, ALP activity assay, real-time RT-PCR and Western blot showed that there was no difference between Penicillin-Streptomycin group and α-MEM group (P>0.05). The expression of TNF-α decreased in Penicillin-Streptomycin group (P<0.01). Conclusions：Penicillin-Streptomycin significantly suppressed the expression of inflammatory cytokines in inflammatory dental pulp stem cells, and has no noticeable effect on the proliferation and differentiation of the cells.