Gold nanoparticles were prepared in PEG10000/Vc/HAuCl4 system with Vc as the reducing agent. Then gold-platinum bimetallic nanoparticles with different Pt/Au ratio were formed using a simple gold seed-mediated growth method by controlling the mass ratio of HAuCl4/H2PtCl6. Their electrocatalysis effects on H2O-2 electrochemical oxidation were studied. Results of Uv-visible spectra (Uv-vis), transmission electronic microscopy (TEM), X-ray diffraction (XRD) and selected area electron diffraction (SAED) show that Au-Pt bimetallic nanoparticles are of face-centered cubic structure. The electrochemical performance of Au-Pt/glassy carbon (GC) electrode was investigated by cyclic voltammetry method. The result indicates that the Au-Pt/GC electrode has good electrocatalytic activity for H2O2 oxidation. The catalytic efficiency is increased with more Pt content in Au-Pt alloys.