The ordered mesoporous carbon (OMC)/paraffin composites were successfully prepared by a facile physical mixing method and an EMI SE of 21-23 dB was achieved at the OMC loading of 5.69 wt.% in the X band. This indicates that the composites are very suitable for an application as effective and lightweight EMI shielding materials. The EMI shielding of the composite shows an absorption-dominant mechanism, i.e., a contribution shift from reflection to absorption is observed with the increase in OMC loading and frequency. This could be explained by the intrinsic properties (electrical conductivity, complex permittivity and potential large defects) and novel structure of the composites.