Colorimetric　and　label-free　plasmonic　biosensors,　relying　on　localized　surface　plasmon　resonance　(LSPR)　on　metallic　subwavelength　structures,　have　significant　potential　for　many　application　areas　such　as　clinical　diagnosis　and　environmental　monitoring　detection　by　simple　instrumentation　or　even　naked　eye.　In　this　paper,　we　present　a　high-performance　colorimetric　and　label-free　plasmonic　biosensors,　consisting　of　an　array　of　three-dimensional　all　-metal　nano-cavities.　The　nanostructures,　composed　of　a　top　array　of　gold　disk,　aluminum　pillar　and　bottom　gold　reflection　film,　are　similar　to　metal-insulator-metal　and　the　insulating　layer　is　air　cavities　that　are　easy　to　be　filled　with　other　gaseous　or　liquid　dielectric.　Therefore,　the　analytes　could　permeate　into　the　nano-scale　cavities　and　enable　strong　light-matter　interactions　there.　The　sensor　shows　significant　color　difference　with　small　refraction　index　changes　and　the　sensitivity　reaches　683.5　nm/RIU.　Moreover,　when　a　monomolecular　layer　of　Dithiobis(succinimidyl　propionate)　(DSP)　was　bonded　to　the　surface　of　the　nanostructure,　the　color　of　the　metamaterials　change　from　blue　to　green　back.　The　metamaterials　will　offer　great　potential　for　detection　and　studies　of　binding　events　between　the　target　analyte　and　its　corresponding　receptor.