Ho3+-doped　(K0.5Na0.5)NbO3-based　transparent　ceramics　have　been　prepared　via　pressureless　solid-state　method.　The　ceramics　possess　moderate　optical　transparency　with　the　energy　band　gap　of　2.9eV　and　submicron-sized　grains　(＜500nm).　The　temperature-dependent　dielectric　properties　and　ferroelectric　polarization-electric　field　hysteresis　loops　demonstrate　that　the　ceramics　own　relaxor-like　characteristics.　The　up-conversion　photoluminescence　and　optical　temperature　sensing　properties　of　the　ceramics　have　been　investigated.　The　temperature　dependence　of　photoluminescence　provides　a　fluorescent　method　to　detect　phase　transitions,　which　can　be　expanded　to　other　ferroelectric　systems.　The　outstanding　optical　temperature　sensitivity　(0.0075/K　at　430K)　of　the　ceramic　is　higher　than　many　other　rare-earth-doped　ceramics　or　glasses.　These　results　suggest　that　the　Ho3+-doped　(K0.5Na0.5)NbO3-based　transparent　ceramics　are　promising　lead-free　transparent　materials　for　multifunctional　applications,　especially　in　temperature　sensing　devices.