To study the bone tissue osteogenesis ability of bone marrow stromal cells (BMSCs) in vitro and in vivo.The BMSCs were separated by gradient centrifugation on Percoll, culture-expanded and induced with a conditional medium. The cells were examined by transmission electron microscopy and histochemistry or immunochemistry stains technique including AKP,Cbfa1,OCN, OPN, BSP and collagen type I. The mRNA of collagen type I in cultured cell was also examined by in situ hybridization.Histochemical studies showed positive stain of AKP,Cbfa1, OCN, OPN,BSP and collagen type I,and in situ hybridization also showed the positive express of mRNA of collagen type I. The excretion of collagen and deposition of calcium salt were observed under transmission electron microscopy.BMSCs cultured in conditional medium shows osteoblast-like functions in vitro, which provides an ideal seed cells for bone tissue engineering.