By using a hot filament chemical vapor deposition (HFCVD) method, deposition of carbon on Si nanowires (Si NWs) has been studied. Multi-walled carbon nanotubes (CNTs) were found to form on the surfaces of Si NWs at 900 degreesC with a good surface coverage and adherence. However, as the temperature of deposition increased to 1000 degreesC, Si cores tended to transform into beta -SiC cores and the carbon layers grown on beta -SiC cores were distorted. When the temperature of deposition was as high as 1100 degreesC, the carbon layers bucked openly to form many feather-like carbon sheets sprouting from the surface of the nanowires. A mixture of large carbon sheets and beta -SiC nanowires was formed when the temperature was over 1300 degreesC.