A series of Co1-xCux (x = 0.05-0.70) composite nanowire arrays have been electrodeposited in alumina templates. An apparent pH value rule for nanowire phase and composition has been found. Based on it, composite nanowires can be obtained and the composition becomes more controllable. In the composite nanowires, the cubic and hexagonal structures coexisted. The specific magnetic properties, coercivity and squareness of the composite arrays are enhanced by three times, apparently preceding to those in single phase nanowires.