The　Ho3+:ZnWO4　single　crystals　were　grown　by　Czochralski　method.　The　absorption　and　fluorescence　spectra　of　Ho3+:ZnWO4　at　visible　and　infrared　range　were　investigated.　The　position　and　splitting　of　the　Stark　energy　levels　of　Ho3+　ions　in　ZnWO4　were　defined　at　room　temperature.　Results　show　that　stronger　fluorescence　emissions　of　the　wavelengths　of　550,　665　and　758　nm　were　observed　at　laser　488　nm　excited,　fluorescence　branch　ratio　of　emissions　is　84.18%,　0.68%　and　15.14%,　corresponding　to　5S2　&rarr　5I8,　5F5　&rarr　5I8　and　5S2　&rarr　5I7,　respectively.　Conversion　of　red　laser　radiation　to　green　5S2　&rarr　5I8　emission　was　observed　at　laser　633　nm　excited,　the　upconversion　process　is　found　to　be　the　step　absorption　of　single　ion.