Abstract: Diamond nanowires is a kind of wide band-gap semiconductor materials. Theoretical evaluation shows that the diamond nanowires has excellent physical and chemical properties, such as negative electron affinity, good chemical inertness, high young's modulus and high hardness, and high thermal conductivity at room temperature. These theoretical study prompted experiments with important feasible development goals, through a lot of efforts to study, synthesis of diamond nanowires has got great development, including ion etching, plasma processing of carbon nanotubes, high temperature and high pressure method, template or catalyst assisted CVD method. This paper summarizes the main preparation methods of diamond nanowires:reactive ion etching and chemical vapor deposition method, and the research progress of diamond nanowires.