CoCu nanowire arrays have been electrodeposited into alumina templates. We demonstrate that the crystal structure and related magnetic properties can be effectively controlled only by applying different deposition potentials. By gradually decreasing the applied voltage from -1.6 to -0.9 V, the main structure dramatically changes from the single-crystal hexagonal Co phase to the cubic alloy phase. The investigation of corresponding magnetic properties indicates that the orientation of easy axis varies from perpendicular to the nanowire axis to parallel to the nanowire axis.