Abstract: The Cu-Ag composite nanoparticles were prepared by a both gas and liquid phases stabilizing method. The structure and morphology and surface layer as well as oxidation resistance of the particles were studied using X-ray diffraction(XRD), high-resolution transmission electron microscopy(HRTEM), infrared spectrum analysis, chemical analysis, gas analysis, and differential thermal and thermogravimetry analysis. The results show that the particle size ranges from 20nm to 150nm. The surface of particles consists of a bi-layer including a terpineol(C₁₀H₁₈O) molecules layer and an oxide one; the bi-layer prevents the particles from further oxidation in air. The terpineol molecules are oxidized at about 220℃ in air. The Cu-Ag composite nanoparticles are violently oxidized at about 340℃ because the terpineol molecules of the surface of the particles are oxidized. At the temperature below 220℃, the oxidation resistance of the Cu-Ag composite nanoparticles prepared by the both gas and liquid phases stabilizing method is better than that by the gas phase stabilizing method.