In order to fabricate effective Pd-Ni alloy nanowire arrays with given compositions and size, the process of nucleation and growth and the dependence of alloy composition on deposition potential were investigated. The results reveal that the compositions and sizes of Pd-Ni alloy nanowires can be controlled within a desired range through adjusting suitable nucleation and growth potentials as well as the time. The Ni content in the alloy nanowires was found to vary from 6 to 28% when the deposition potential was changed from -0.3 to -1.9 V. A growth potential of -0.35 to - 0.50 V was applied to fabricate Pd-Ni alloy nanowires with 8-15% Ni content. Continuous and parallel nanowire arrays can be successfully fabricated when nucleation is performed at a potential of -1.2 V for 50 ms with further growth at -0.45 V for 800 s. Pd-Ni crystal phases exist in the alloy structure forms of {111}, {200}, {220}, {311}. The nanowires have an average diameter of 150 nm and a length of 100-450 mu m.