The　development　of　near-infrared　(NIR)-responsive　upconversion　nanoplatforms　for　photodynamic　therapy　(PDT)　has　attracted　considerable　attention　in　recent　years,　but　is　still　limited　by　the　low　PDT　efficacy.　Herein,　we　designed　and　synthesized　a　NIR-responsive　nanoplatform　through　the　integration　of　lanthanide-doped　upconversion　nanoparticles　(UCNPs),　Pt-decorated　porphyrin　metal-organic　frameworks　(PMOFs)　and　NIR　dye　IR808　into　a　core-shell　structure　for　highly　efficient　antibacterial　PDT.　The　PMOF　shell　can　function　not　only　as　a　photosensitizer　to　absorb　the　upconversion　luminescence　(UCL)　of　UCNPs　for　singlet　oxygen　(O-1(2))　generation,　but　also　as　a　porous　host　material　for　loading　of　IR808.　Remarkably,　we　demonstrated　that　the　heavy-atom　effect　of　Pt(II)　can　simultaneously　enhance　the　intersystem　crossing　(S-1　-＞　T-1)　efficiencies　of　the　IR808　and　the　porphyrin　ligand　Pt-TCPP,　resulting　in　the　enhancement　of　dye-triplet-sensitized　UCL　of　UCNPs　and　O-1(2)　production　capacity　of　the　photosensitizer.　As　a　result,　the　proposed　nanoplatform　exhibited　excellent　O-1(2)　production　and　a　significant　bactericidal　activity　against　methicillin-resistant　Staphylococcus　aureus　(MRSA)　with　5.27　log(10)　(＞　99.999%)　killing　efficacy.　These　findings　will　pave　the　way　for　designing　highly　efficient　PDT　nanoplatforms　and　accelerate　their　biomedical　applications.