Upconversion　nanocrystals　have　a　lot　of　advantages　over　other　fluorescent　materials.　However,　their　applications　are　still　limited　due　to　their　comparatively　low　upconversion　luminescence　(UCL).　In　the　present　study,　a　novel　nanocomposite　of　Ag/graphene@SiO2-NaLuF4:Yb,Gd,Er　for　enhancing　UCL　was　fabricated　successfully,　and　its　morphology,　crystalline　phase,　composition,　and　fluorescent　property　were　investigated.　It　is　interesting　to　find　that　the　Ag/graphene@SiO2-NaLuF4:Yb,Gd,Er　and　Ag@SiO2-NaLuF4:Yb,Gd,Er　nanocomposites　showed　high　UCL　enhancements　of　52-　and　10-fold　compared　to　the　control　of　Ag-free　nanocomposite　SiO2-NaLuF4:Yb,Gd,Er　respectively.　The　enhancement　of　52-fold　is　greater　than　those　reported　in　our　previous　studies　and　some　papers.　Moreover,　the　measured　life　times　of　the　Ag-presented　nanocrystals　were　longer　than　that　of　Ag-absent　counterparts.　These　enhancements　of　UCL　can　be　ascribed　to　the　effect　of　metal-enhanced　fluorescence,　which　is　caused　by　the　enhancement　of　the　local　electric　field.　The　UCL　intensity　of　Ag/graphene@SiO2-NaLuF4:Yb,Gd,Er　was　5.2-fold　higher　than　that　of　Ag@SiO2-NaLuF4:Yb,Gd,Er,　indicating　that　graphene　presented　in　the　fabricated　nanocomposite　structure　favors　metal-enhanced　UCL.　The　small-sized　Ag　nanoparticles　anchored　on　the　graphene　sheet　mutually　enhanced　each　other＇s　polarizability　and　surface　plasmon　resonance,　resulting　in　a　big　metal-enhanced　UCL.　This　study　provides　a　new　strategy　for　effectively　enhancing　the　UCL　of　upconversion　nanocrystals.　The　enhancement　potentially　increases　the　overall　upconversion　nanocrystal　detectability　for　highly　sensitive　biological,　medical,　and　optical　detections.