Aiming　at　poor　efficiency　of　the　traditional　materials　in　low-mid　frequency　sound　absorption　and　its　narrow　bandwidth,　we　present　an　ultra-broadband　acoustic　metamaterial　that　can　achieve　near-perfect　continuous　absorption　within　380　Hz–3600　Hz　with　a　thickness　of　only　7.2　cm.　Its　basic　cell　is　constructed　by　turning　the　original　neck　of　a　Helmholtz　resonator　into　multiple　smaller　ones,　and　the　neck　panel　becomes　into　a　micro-perforated　panel　(MPP).　By　coupling　the　characteristics　of　the　cavity＇s　multi-order　resonance　and　the　MPP＇s　broadband　absorption,　the　cell＇s　high-order　impedances　can　be　tuned　to　more　match　that　of　the　air　medium.　The　cell　can　therefore　obtain　multiple　excellent　high-order　absorption　peaks　besides　the　original　one;　meanwhile　all　the　peaks　can　become　broader　resulting　from　the　larger　energy　leakage　rate.　On　this　basis,　a　subwavelength　12-cell　sample　is　obtained　of　which　the　absorption　band　is　broadened　almost　100%　by　the　high-order　peaks　and　has　an　average　absorption　coefficient　above　90%.　Characterized　by　the　extraordinary　absorption　performance,　thin　thickness,　and　easy-fabricated　structure,　this　proposed　metamaterial　has　great　potential　in　noise　control　engineering　applications.　©　2020　Elsevier　Ltd