Self-assembly metal/semiconductor heterostructured Cu-Ge alloy nanowires were successfully synthesized by using the anodic aluminum oxide (AAO) template-assisted vacuum casting process for the first time, analyzed their interface microstructures and fabricated single nanowire into device. AAO, a membrane with a controllable microstructure of nano-channel array, was utilized to synthesize nanowires of the identical stoichiometry to bulk materials, combining with solid-liquid-solid transformation process. Through choosing a suitable hypoeutectic or hypereutectic composition ratio the size effect will force the phases of nanowires to solidify alternatively along axial direction. Thus, self-assembly nanowires with an alternative metal/semiconductor heterostructure can be obtained. Furthermore, a single nanowire device was synthesized to investigate the relative electrical properties for semiconductor applications. This results are useful in developing metal/semiconductor heterostructured nanowires for advanced FET devices. Figure 1