Abstract: As a new kind of radar absorbing material , carbon nanotubes show an excellent wave absorbing propertyin a wide f requence range because of their special st ructures and elect romagnetic properties. Moreover , they haveother characteristics such as light weight and good stability , so they are considered to be promising. In this paper ,the radar absorbing property was studied for MWCNTs/ GF/ epoxy composites in millimeter wave (f rom 26. 5 to4010 GHz) with the same thickness and different content s of MWCNTs or different thickness and the same contentof MWCNTs. The result s show that the radar absorbing property of this kind of composites is improved withincreasing the content of MWCNTs. The out standing radar absorbing property of MWCNTs/ GF/ epoxy compositesis due to not only the radar absorbing property of MWCNTs , but also the resonant absorbing property of composites.The test result s calculated with elect romagnetic parameters such as relative dielect ric parameter and relative magneticconductive ratio of this kind of composites are in agreement with the absorbing theory.