Abstract: Short carbon fibers were treated at temperatures around 1100°C in a furnace through chemical vapor infiltration technology. The fiber surface was observed by scanning electron microscopy. The reflectivity of electromagnetic radiation by the composites that were reinforced by surface-treated carbon fibers and by as-received ones was measured in the frequency range of 8.0–18.0GHz. The reflectivity for different carbon fiber contents of 0.2%, 0.4%, 0.6% and 1.0wt% was investigated. Results showed that the reflectivity of the composites that were reinforced by untreated carbon fibers tended to increase with the increasing fiber contents. The minimum reflectivity was −19.3dB, far less than −10dB, when the fiber content was 0.4% and there were wave-absorbing properties. However, after surface treatment, the minimum reflectivity was −8.1dB for the same fiber content of 0.4%, indicating significant wave-reflecting properties. The achieved reflectivity values after surface treatment were generally greater than those without treatment. [Copyright &y& Elsevier]