We have successfully synthesized a new class of dispersed non-Pt catalysts with sub-10 nm size by the ultrasound-assisted polyol syntheses method. The as-prepared PdCu alloy is either a sigle, fcc-type phase or phase-segregated into domains of chemically ordered bcc- and chemically disordered fcc-type structure. The lattice parameter of the PdCu catalysts was shown to increase with increasing Pd%. The PdCu alloys have revealed a synergistic correlation between the catalytic activity, atomic-scale structure and composition. In addition, electrochemical measurements indicate that the PdCu alloys exhibit substantially highly active and durable catalytic properties for methanol oxidation, ascribed to the well-dispersed nanoparticles, and the possible synergistic and electronic effect between these two metals. We trust that our efforts not only pave a new way for preparing the highly-dispersed nanocatalysts with small size, but also provides an effective strategy to synthesize non-Pt methanol oxidation reaction catalysts with enhanced catalytic performance.