A　novel　room　temperature　self-healing　carbonyl　iron　powder/　polydopamine@　multi-walled　carbon　nanotubes　(CIP/PDA@MWCNTs)　composites　as　microwave　absorber　covering　the　whole　X　frequency　band　were　prepared　in　this　study.　In　order　to　improve　the　impedance　matching　and　dispersion　of　CIP　in　composites,　it　was　encapsulated　by　PDA　to　form　a　core-shell　structure.　Meanwhile,　the　polydopamine　modified　carbonyl　iron　powder　(CIP/PDA)　was　mixed　with　MWCNTs　to　enhance　the　performance　of　microwave　absorption,　so　that　the　the　composites　possessed　dielectric　and　magnetic　losses.　Moreover,　the　composites　have　self-healing　property.　When　the　content　of　CIP/PDA@MWCNTs　is　20　wt%,　the　minimum　reflection　loss　of　the　self-healing　composites　is-30.69　dB,　and　the　bandwidth　of　RL　less　than-10　dB　can　reach　up　to　9.44　GHz,　covering　the　entire　X.　Therefore,　this　room　temperature　self-healing　CIP/PDA@MWCNTs　composite　will　become　an　ideal　microwave　absorbing　material　for　novel　function　device.