Abstract: Copper nanoparticles were synthesized by the flow-levitation method and they were coated with the carbon-and-hydrogen films through the hollow-cathode glow discharge(HCGD). The growth mechanism of the coating films was described. The HCGD with a voltage of 450 V was used for producing CH plasma. The input fluxes of H2 and CH4 were 12 ml/min and 6 ml/min, respectively. The distance from the sample step to the bottom of the cathode was 2 cm. The working pressure was 100 Pa and the deposition velocity was 7.5 nm/min. The coated Cu nanoparticles and uncoated ones were observed with transmission electron microscopy. Cu nanoparticles were spherical but not very well defined, and the particle size ranged from 10 nm to 100 nm in diameter. The coating thickness was about 15 nm for most of the nanop