Osteogenesis deep in the materials is postponed because the blood vessels grow into the materials very slowly. It is one of the key challenges to the bone tissue engineering researchers. However, it was found that marrow stromal cells can produce vascular endothelial growth factor (VEGF) while endothelial cells produce bone morphogenetic protein (BMP). So we presume if we have co-culture of marrow stromal cells and endothelial cells on the biomaterials, osteogenesis and angiogenesis may be promoted simultaneously. In this experiment, we compare the alkaline phosphatase (ALP) activity and osteocalcin (OCN) production of three groups: the marrow stromal cells under activation of endothelial cells culture fluid, the induced marrow stromal cells, and the untreated marrow stromal cells. The results reveal that the ALP activity and OCN production of the marrow stromal cells under activation of endothelial cell culture fluid and the ALP activity and OCN production of the induced marrow stromal cells do not show statistically significant difference, but they are significantly higher than those of the untreated marrow stromal cells (P < 0.01). It is concluded that the VEGF in the endothelial cell culture fluid can promote osteogenesis as effective as osteogenic induction medium can do.