Objective To explore the intervention effects of trichostatin A ( TSA ) on specialization of ratbone marrow mesenchymal stem cells ( MSCs ) .Methods The rat MSCs were isolated, cultured and purified by the whole bone marrow adherent methodin vitro, with morphological observation.The third generation of MSCs were selected, directional induced to osteoblasts, and divided into the TSA low dose group (0.1μmol/L), middle dose group (1μmol/L) , the high dose group (10μmol/L) according to different drug concentrations, seting up blank control group at the same time.MSCs proliferation and cellgrowth curve of each group were drawn by MMT, the activity of alkaliphosphatase ( ALP) was detected, and the levels of corebinding factor α1 (Cbfα1), basic fibroblast growth factor (bFGF) and insulin-like growth factors-1 (IGF-1) mRNA were detected by RT-PCR. Results The trend of MSCs growth curves in each groups were similar, compared with control group, the growth curve of TSA low dose group had no significant change, the TSA middle dose and high dose significantly promoted the proliferation of MSCs (P<0.05).Compared with control group, ALP activity of TSA low-, middle-and high-dose group were significantly higher at 4th,5th,6th(P<0.05).The expression levels of Cbfα1, bFGF and IGF-1mRNA were significantly higher than those of control group, respectively (P<0.05).Conclusion TSA can significantly promote the ratbone marrow mesenchymal stem cells to differentiate into osteoblast, which is possibly associated with up-regulation of Cbfα1, bFGF and IGF-1mRNA level.