Drynariae Rhizorna (DR), an herbal medicine known for its effect to purify blood quality and improve circulation, frequently appears as the main ingredient in prescriptions for bone injuries. Currently, how pharmacologically it contributes to the reformation of bone is unclear. In the present study, the effect of the aqueous extract of DR on bone cells was investigated in vitro for the first time. The human osteoprecursor cells (OPC-I) were incubated in the medium with different concentrations of the aqueous extract of DR and the cell proliferation was studied. When the concentration of DR aqueous extract was $<120{;}mu extrm{g}/ml$, the proliferation of OPC-I was enhanced. However, the proliferation of OPC-I was inhibited by DR extract with the concentrations $>250{;}mu extrm{g}/ml$. Under most treatments, the cells presented very pale expression for cyclooxygenase-2 (Cox 2) protein; a slightly intensified band showed at the highest DR concentration, 1.0 mg/ml during the course of culture. From the results, it was concluded that the aqueous extract of DR was found to directly stimulate the proliferation, alkaline phosphatase (ALP) activity, protein secretion and particularly type I collagen synthesis of OPC-I at dose-dependent manner.