Objective:To study the effects of trichostatin A(TSA) on the osteogenic differentiation of rat adipose-derived stem cells(ADSCs) in two-dimensional tissue culture plastic and three-dimensional nano-hydroxyapatite/collagen(nHAC) scaffold. Methods:ADSCs were cultured in two-dimensional tissue culture plastic (TCPT) and three-dimensional nHAC(nHACT) which contained 75 nmol/L TSA,and two groups without TSA(the TCP group and the nHAC group) were set as control. One and three days after ADSCs seeded onto the nHAC scaffold,the cells were characterized by field emission scanning electron microscope(FESEM). The alkaline phosphate(ALP) activity was detected to evaluate the early osteogentic differentiation at 3,5,7 d. Western blot was performed to detect the expression of Runx2,OPN and BMP2 proteins. Results:On nHAC,ADSCs were well adhered to and fully extended on the scaffold with TSA. ADSCs on TSA treated scaffold presented better. The data of ALP was continuously increased at 3,5,7 d. The highest expression of ALP occurred in nHACT had significant difference between groups(P < 0.05). Western blot demonstrated that Runx2,OPN and BMP2 protein in the nHACT groups increased more evidently than the other groups,with the same trends as ALP results. Conclusion:TSA could improve the early osteogentic differentiation of ADSCs,especially in the three-dimensional nHAC scaffold.