The third-generation hyperbranched polyester (HBPE-3) was synthesized with pentaerythrite as core molecule and 2, 2-dimethylol propionic acid as AB2 monomer using step by step polymerization process at first. Then the Ag-Cu alloy particles were synthesized in HBPE-3 by a reductive technique. The synthesized hyperbranched polyester and Ag-Cu alloy particles were characterized by Fourier transform infrared spectroscopy (FT-IR), UV-visible absorption spectra (UV-vis), X-ray diffraction, laser light scattering, scanning electron microscopy (SEM) and thermogravimetric (TG). The results show that there exists HBPE-3 on the Ag-Cu alloy particles surface. The Ag-Cu alloy particles have strong absorption peaks at around 210 and 450 nm. The XRD patterns of Ag-Cu alloy particles are in agreement with the standard cards. Most of particle sizes of Ag-Cu alloy particles are around 1.2 μm. The Ag-Cu alloy particles have good thermal stability.