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　∼350　nm,　uniform　grain　distribution,　low　porosity　and　high　density.　The　optical　transmittance　of　0.3-mm　ceramic　is　up　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.　©　2019　Elsevier　B.V.