The　upconversion　luminescence　at　the　visible　band　was　excited　by　the　high　power　density　whispering　gallery　mode　(WGM)　on　the　surface　of　the　microsphere.　Under　the　WGM　excitation,　Er3+　of　NaYF4:Er3+　directly　absorbed　three　photons　at　1525　nm,　followed　by　the　generation　of　upconversion　luminescence.　We　used　WS2　quantum　dots　(QDs)　as　donors　and　NaYF4:Er3+　upconversion　nanoparticles　(UCNPs)　as　acceptors　to　enhance　upconversion　luminescence　by　Forster　resonant　energy　transfer　(FRET).　The　physical　mixture　composed　of　monolayer　WS2　and　NaYF4:Er3+　nanoparticles　was　coated　on　SiO2　microsphere　by　immersion　method.　Excited　by　high　power　density　WGM,　three　photons　were　absorbed　by　WS2-QDs　based　on　the　quantum　size　effect　to　generate　excited　electrons　as　donors　and　UCNPs　as　acceptors　based　on　FRET,　subsequently,　the　energy　of　the　electrons　were　transferred　to　the　luminescence　center　Er3+　to　improve　the　upconversion　luminescence　efficiency.　The　mechanism　model　of　upconversion　luminescence　enhancement　based　on　FRET　of　WS2-NaYF4:Er3+　was　proposed,　and　the　enhancement　effect　was　experimentally　studied　and　demonstrated.　To　study　the　distance　dependence　of　energy　transfer　between　QD　and　UCNP　pairs,　we　covered　the　surface　of　the　silica　microsphere　with　a　controlled　concentration　of　WS2　mixed　with　NaYF4:Er3+　nano-particles.　When　the　mixed　concentration　of　WS2-QDs　was　0.15%,　the　upconversion　luminescence　reached　the　highest　efficiency.　The　results　showed　that　a　twofold　upconversion　luminescence　enhancement　can　be　experimentally　achieved.　The　proposed　approach　for　enhancing　the　upconversion　luminescence　could　benefit　the　improvement　of　imaging　signal-to-noise　ratio　(SNR)　using　UCNPs　for　fluorescent　labels　in　life　sciences.