This study was aimed to construct a two-dimensional culture system by using osteoblasts induced from human marrow mesenchymal stem cells (MSC) and to investigate its support effect on survival of hematopoietic stem/progenitor cells for umbilical cord blood (UCB) ex vivo. MSCs were isolated from adult human bone marrow and were cultured, the second generation of MSCs were induced into osteoblasts which were irradiated with 20 Gy gamma rays in a Cobalt 60 source and confluenced into a feeder layer. CD34(+) cells were selected from fresh umbilical cord blood samples by using Microbead Kit of MiniMACS and seeded into the two-dimensional culture system to culture ex vivo without exogenous cytokines. By using colony-forming assay, high proliferative potential colony-forming cell assay, and long-term culture initiating cell assay, the ability of the two-dimensional system to culture HSCs/HPCs was observed. The results showed that the osteoblasts induced from bone marrow MSC in constructed two-dimensional culture system displayed more significant support effect on survival of hematopoietic stem/progenitor cells from umbilical cord blood (UCB) ex vivo, compared with other culture systems, especially on long term HSCs survival ex vivo. It is concluded that the two-dimensional culture system constituted by osteoblasts induced from human MSCs has certain ability of supporting maintenance and multipotency of HSCs/HPCs from umbilical cord blood in vitro, especially sustaining survival of HSC in long-term culture. It has also been proved that osteoblasts play a crucial role in regulation of HSC growth.