Graphene　has　some　outstanding　properties　in　the　photoelectric　field,　especially　ultra　fast　response　and　broad　spectrum　absorption,　which　have　led　to　strong　attraction　on　graphene　photodetector.　However,　the　photoresponsivity　of　pure　graphene　device　is　below　10　mA　W-1.　It　would　limit　the　application　of　graphene　photodetector.　Here,　we　design　a　metamaterial　structure　with　a　broadband　high　absorption　spectrum.　And　by　integrating　it　into　the　graphene　photodetector,　the　high　photoresponsivity　of　a　pure　graphene　photodetector　in　a　broadband　range　could　be　acquired.　The　photoresponsivity　of　photodetector　can　achieve　nearly　200　mA　W(-1)which　is　two　orders　higher　than　the　one　of　pure　monolayer　graphene　photodetector.　Besides,　the　photodetector　also　keeps　the　broadband　photoresponse.　The　hot　carriers　can　be　generated　by　coupling　of　multiple　resonances　and　effectively　transported　to　graphene　with　the　advantage　of　ultrathin　metal　film.　Based　on　this　work,　more　potential　applications　of　graphene　photodetector　could　be　developed　in　some　related　fields.