Aim To investigate the plasticity of bone marrow stromal stem cells(MSCs) along endothelial lineage under different culture condition. Methods The human MSCs were isolated by density gradient centrifugation. Fluorescence activated cell sorter (FACS) was used to analyze the phenotypic characteristics of MSCs. Fluorescence Immunocytochemistry was used to observe the vWF and/or Flk-1 protein expression of MSCs after cultured with DMEM medium containing 50 μg/L VEGF, 5 μg/L bFGF, 100 mg/L ECGS or with endothelial cells(ECs) conditioned medium or cocultured with mature rabbit ECs for 5 days. Results FACS analysis indicated that the MSCs did not express CD34 (CD34 expressing cells vs negative control: 4.16%±0.16% vs 4.06%± 0.23 %, n=6, p>0.05), but expressed CD105 and CD166 (CD105 expressing cells vs negative control: 90.20%±2.35% vs 4.06%±0.23%; CD166 expressing cells vs negative control: 82.30%±3.22% vs 4.06%±0.23%, n=6, p<0.05). 33.42% MSCs began to express vWF after cultured in DMEM containing VEGF, bFGF and ECGS. 25.71% MSCs began to express Flk-1, but did not express vWF after cocultured with mature ECs for 5 days. The MSCs did not express Flk-1 or vWF after cultured in ECs conditioned medium. Conclusions Cytokines and mature ECs could induce MSCs to differentiate alone endothelial lineage, while ECs conditioned medium could not.