Transparent　Er3+/　La3+　co-doped　(K0.5Na0.5)NbO3　ceramic　was　prepared　by　pressureless　sintering.　The　XRD　result　shows　that　it　possesses　high　symmetrical　pseudo-cubic　perovskite　structure　without　impurity　phase.　The　ceramic　owns　fine　grains　with　the　average　size　of　similar　to　350　nm,　uniform　grain　distribution,　low　porosity　and　high　density.　The　optical　transmittance　of　0.3-mm　ceramic　is　up　to　similar　to　60%　in　the　visible　region.　Additionally,　the　ceramic　has　good　dielectric　properties　with　the　relaxor-like　behavior.　Under　an　excitation　of　980-nm,　the　temperature-dependent　up-conversion　luminescent　color　of　Er3+　is　stable　below　523　K　and　adjustable　(changing　from　green　to　tangerine　color　as　temperature　increases)　above　523　K.　The　ratio　of　red　to　green　emission　intensity　with　temperature　can　provide　a　non-contact　luminescent　route　to　roughly　detect　the　phase　transition　of　this　ferroelectric　ceramic.　Furthermore,　the　fluorescence　temperature　sensing　performance　of　the　ceramic　was　investigated　and　the　maximum　sensitivity　is　0.003/K　at　380　K.　Due　to　optical,　PL　and　electrical　properties,　the　transparent　ceramic　shows　potential　in　the　application　of　electro-optical　coupling　devices.