Surface　modification　via　low-temperature　plasma　has　an　extensive　application　prospect　in　different　engineering　fields　due　to　its　comprehensive　merits　in　facilitating　the　introduction　of　functional　groups　and　creating　more　heterogeneous　interfaces.　Herein,　a　simple　high-temperature　plasma　method　is　developed　to　get　novel　multiple-phase　nanocomposites　of　core-shell　Fe/FeN/Fe3C@GN　nanoparticles　with　bifunctional　characteristics　of　microwave　absorption　(MA)　and　anti-corrosion.　And　then,　we　further　investigate　the　MA　properties　of　Fe/FeN/Fe3C@GN　nanoparticles　after　low-temperature　NH3　plasma　etching.　It　is　found　that　surface　modification　of　Fe/FeN/Fe3C@GN　nanoparticles　can　generate　remarkable　changes　in　specific　surface　areas,　Raman　features　and　MA　properties　of　these　nanocomposites.　The　Fe/FeN/Fe3C@GN　nanoparticles　after　NH3　plasma　etching　possess　excellent　MA　properties　with　an　optimal　reflection　loss　(RL)　of　-51.0　dB　at　an　ultra-thin　thickness　of　1.9　mm　with　a　low　filling　content　of　30　wt%　and　the　corresponding　effective　absorption　bandwidth　(EAB　＜　-10　dB)　up　to　4.7　GHz　(13.3-18.0　GHz).　The　fascinating　MA　properties　of　etched　Fe/FeN/Fe3C@GN　nanoparticles　may　be　attributed　to　the　cooperative　effect　of　several　points:　(i)　The　NH3　plasma　etch　introduces　a　large　number　of　polar　functional　groups,　which　can　be　regarded　as　the　polarization　center　to　produce　more　polarization　loss;　(ii)　The　appropriate　dielectric　loss　and　impedance　matching　achieve　a　good　balance,　and　the　abundant　heterogeneous　interface　significantly　enhances　the　polarization　relaxation　loss;　(iii)　The　existence　of　hetero-nanostructure　further　improves　the　multiple　reflections　and　scattering　of　the　propagating　microwaves.　In　addition,　this　work　provides　a　new　strategy　for　the　design　and　fabrication　of　core-shell　MA　materials.