The　external　quantum　efficiency　(EQE)　enhancement　of　different　sized　GaN　micro-light-emitting　diodes　(mu　LEDs)　by　using　localized　surface　plasmons　(LSPs)　have　been　studied.　Silver　nanoparticles　(Ag　NPs)　are　attached　to　the　sidewalls　of　mu　LEDs　by　spin-coating　so　as　to　be　effectively　coupled　with　the　multiple　quantum　well　(MQW)　of　mu　LEDs　and　generate　the　LSPs.　In　the　mu　LEDs　with　20　x　20　mu　m2　large　mesas,　the　LSPs　can　effectively　inhibit　the　efficiency　droop.　Compared　to　the　mu　LED　samples　without　the　LSPs　coupling,　the　EQE　has　been　enhanced　by　about　8%　at　a　high　current　density　of　20,000　A/cm2.　This　work　confirms　the　effectiveness　of　the　LSPs　technology　in　improving　the　mu　LED　performances,　which　is　originally　practiced　only　on　the　basal　faces　of　conventional　LEDs.