In　this　paper　we　report　the　infrared　to　visible　upconversion(UC)　luminescence　properties　of　Hf4+　and　Zr4+　codoped　NaYF4:　Yb3+/Tm3+.　Samples　were　synthesised　by　hydrothermal　method.　Concentration　of　Tm3+　and　Yb3+　ions　were　fixed　to　be　2　mol%　and　5　mol%　for　all　samples,　respectively.　NaY0.93-xYb0.05Tm0.02F4　was　tridoped　with　0,　2,　4,　6,　8　mol%　Hf4+　or　Zr4+　and　corresponding　samples　were　named　as　Hf0,　Hf2,　Hf4,　Hf6,　Hf8　and　Zr0,　Zr2,　Zr4,　Zr6,　Zr8,　respectively.　In　a　typical　procedure,　trivalent　nitrate　stock　solutions　of　0.2　mol/L　were　prepared　at　first　by　dissolving　the　corresponding　metal　oxide　in　concentrated　nitric　acid　or　hydrofluoric　acid　at　elevated　temperatures.　And　then,　a　certain　mole　percentage　of　trivalent　nitrate　solutions　were　added　into　20　mL　0.04　mmol　EDTA　aqueous　solution.　After　vigorous　stirring　for　30　min,　25　mL　ethanol　solution　containing　0.2　mmol　NaF,　0.2　mmol　NH4HF2　and　corresponding　stoichiometric　amount　Hf4+　or　Zr4+　were　dropwise　added　into　the　solution,　and　then　pH　value　of　solution　was　adjusted　to　3.0　by　addition　1　mol/L　HF,　and　stirring　continued　for　30　min.　Then　the　emulsion　mixture　was　moved　to　PTFE-lined　high　pressure　pot　and　incubated　in　oven　at　180　degrees　C　for　12　h.　The　final　products　were　collected,　washed　several　times　with　water　and　ethanol　alternately,　and　gathered　by　centrifugation,　and　then　dried　in　oven　at　60　degrees　C.　Crystal　microstructure,　morphology　and　UC　luminescence　properties　of　samples　were　investigated　by　X-ray　diffraction,　field　emission　scanning　electron　microscopy,　transmission　electron　microscopy,　X-ray　photoelectron　spectroscopy　and　upconversion　photoluminescence　spectra.　Results　revealed　the　bond　distance　of　F-1-Y　and　F-2-Y　become　close　with　the　rising　of　Hf4+　or　Zr4+　codoped　concentration,　indicating　crystal　field　asymmetry　of　rare　earth　ions　were　tuned　effectively　by　Hf4+　or　Zr4+　codoping.　Electron　hypersensitive　transition　was　promoted,　and　the　intensity　of　802　nm　emission　was　enhanced　obviously.　Hf4+　ion　was　a　better　dopant　than　Zr4+,　for　the　extranuclear　electronic　structure　of　Hf4+　was　the　same　with　rare　earth　ions,　and　Hf4+　ion　was　involved　in　UC　process　as　a　migrator　to　improve　Tm3+　upper　state　levels＇population.　UC　luminescence　of　Hf4+　codoped　sample　were　enhanced　obviously,　especially　the　shortwave　emissions.　The　reported　work　establishes　the　understanding　of　Hf4+　as　a　migrator　for　Tm3+　ions　upconversion　luminescence,　which　may　be　helpful　for　design　and　synthesis　of　high-performance　upconversion　materials.