The　Pt　nanoparticles　(NPs),　which　posses　the　wider　tunable　localized-surface-plasmon　(LSP)　energy　varying　from　deep　ultraviolet　to　visible　region　depending　on　their　morphology,　were　prepared　by　annealing　Pt　thin　films　with　different　initial　mass-thicknesses.　A　sixfold　enhancement　of　the　357　nm　forward　emission　of　ZnMgO　was　observed　after　capping　with　Pt　NPs,　which　is　due　to　the　resonance　coupling　between　the　LSP　of　Pt　NPs　and　the　band-gap　emission　of　ZnMgO.　The　other　factors　affecting　the　ultraviolet　emission　of　ZnMgO,　such　as　emission　from　Pt　itself　and　light　multi-scattering　at　the　interface,　were　also　discussed.　These　results　indicate　that　Pt　NPs　can　be　used　to　enhance　the　ultraviolet　emission　through　the　LSP　coupling　for　various　wide　band-gap　semiconductors.