Abstract: Carbon nanotubes(CNTs) and carbon nanotubes modified by rare earth oxides were used as an absorber of radar waves.The absorber and epoxy resin were blended to prepare radar absorbing materials (RAM) by supersonic dispersion.The polymer pastes were then put into an aluminum matrix to prapare the sample.Carbon nanotubes were characterized by TEM.The radar absorbing properties were tested by RAM measuring system of arch method reflectivity.The radar wave absorbing properties of carbon nanotubes were substantially improved after modification by rare earth oxides.The highest absorbing peak of the sample was -29.10dB at 10.88GHz and had a bandwidth of 7.68 GHz(R＜-10dB) and 10.60GHz (R＜-5dB)respectively.