Abstract: The conductive poly-aniline (PANI) was synthesized by the chemical oxidation method，and the composite absorbents 
of carbonyl iron powder/polymethacrylate (CIP/PMMA) with core-shell structure and carbonyl iron powder/polymethacrylate/poly-aniline (CIP/PMMA/PANI) with two-coating structure were prepared by in-situ composite technique，using aniline，carbonyl iron powder and methacrylate. The structure and morphology of three absorbents were characterized by XRD，SEM and TEM. The electromagnetic parameters of them were measured by using vector network analyzer，and the results show that the CIP/PMMA/PANI composite absorbent has both electric losses and magnetic losses. When the thickness of the material is 1.0 mm，its least reflectivity of computing is -11.26 dB in 2～18 GHz frequency range，and the bandwidths for-10 dB and for -8 dB are respectively 9.2 GHz and 14 GHz. The computing results show that the composite absorbent has a better broad-frequency absorbing property.