Abstract: Objective　To investigate the methods of isolation, cultivation and amplification of Bone marrow mesenchymal stem cells (BMSCs) and the feasibility of inducing BMSCs to differentiate to myofibroblast with exogenous Transforming growth factor-1 (TGF-β1) in vitro to provide the theory for jaw fibrosis induced by radiation .Methods The Bone marrow mesenchymal stem cells (BMSCs) were obtained from rats’ Bone marrow of femur，and the isolation and cultivation were processed by all cultivation；The passage Ⅲ cells were exposed to two kinds of defined mediums for phenotype differentiation. After two weeks of induction, the morphological change of cells was observed in Microscope; Real-time PCR was used to detect cells’ gene expression；the identification of α-SMA and collagenous fiber was pursued by immunohistochemistry．Results　Bone mesenchymal stem cells could be isolated from bone marrow tissue of the rat femoral; the morphology of spindle and shuttle was similar to fibroblast; after directional induction by TGF-β1, the cells showed the characteristics of Myofibroblasts (α-SMA +) accompanied with the increase of COLⅠ、COLⅢ and α-SMA. Conclusion　Bone marrow mesenchymal stem cells, which have stable biological characteristics, can be isolated from the rat femoral bone marrow tissue; TGF-β1 can induce BMSCs to differentiate to Myofibroblast directly, which provides the theory for fibrosis of jaws induced by radiation in vitro.