A　tunable　broadband,　polarization　insensitive　and　incident　angle　insensitive　metamaterial　terahertz　absorber　is　proposed,　which　consists　of　silicon　semi-ellipsoid/semi-spherical　structure,　graphene,　dielectric　layer　and　metal　back　plate.　Based　on　the　known　results,　the　electric　field　results　under　different　chemical　potentials　of　graphene　and　different　structural　conditions　were　analyzed　by　simulation　under　the　condition　of　vertical　incident　TE　wave　show　that　under　the　synergism　of　continuous　and　multimode　Fabry-Perot　resonances　formed　by　silicon　semi-ellipsoid/semi-spherical　subwavelength　structure　and　multiple　discrete　plasma　resonances　excited　by　graphene　the　absorption　spectrum　is　smoothed　and　expanded　so　that　the　structure　can　achieve　a　wide　range　of　adjustable　absorptivity　and　a　broadband　absorption　characteristic　of　nearly　100%　absorptivity.　When　the　chemical　potential　of　graphene　is　around　0.2　eV　and　0.9　eV,　it　can　obtain　about　5.7　THz　and　7　THz　wideband　terahertz　wave　absorption　(the　absorption　rate　is　more　than　90%),　respectively,　and　its　maximum　absorption　rate　is　close　to　perfect　absorption　(about　99.8%).　In　addition,　the　structure　is　insensitive　to　360°　polarization　and　incident　angle　higher　than　60°.　In　the　above　angle　range,　the　absorptivity　of　the　absorber　can　still　be　maintained　to　more　than　90%.　and　the　structure　has　potential　applications　in　terahertz　wave　detection,　spectral　imaging　and　stealth　technology.　©　2022　Chinese　Society　of　Astronautics.　All　rights　reserved.