Nonunion is one of the most common complications after bone fractures. The factors impacting bone healing by mechanical manner have been greatly corrected by advanced surgical techniques and improved osteosynthesis. Additionally, the bone autograft with cancellous bone is the most safe and efficient remedy for nonunion, although all the traditional ways have corresponding limitations. Here comes the tissue engineering technology based on stem cells transplantation opened new horizon in the field of bone regeneration, including embryonic stem cells, adult stem cell and adult osteoblast used for transplantation. Mesenchymal stem cells (MSCs), the adult multipotential stem cells, are important choice for clinical application, with advantages of wide distribution in human tissue, rapid proliferation in vitro and high potential of osteogenesis. The MSCs can be used by gener ally intravenous injection, locally direct injection in the nonunion region, seeding on synthetic scaffolds, and transforming in the gene-modified form. Despite the fact that most methods stay in animal experiment and only a small number of these strategies are used in the clinical setting, mesenchymal stem cells still have great potential value in treatment of bone nonunion.