Er-doped　K0.5Na0.5NbO3-SrTiO3　transparent　ceramics　were　fabricated　by　traditional　pressureless　sintering.　The　dual　effects　of　Er3+　and　SrTiO3　contents　on　the　microstructures,　optical　transparencies　and　optoelectronic　properties　of　the　ceramics　were　investigated.　The　introduction　of　Er3+　and　Sr2+　results　in　decreasing　grain　size　and　generating　cation　vacancies,　affecting　the　density　and　uniformity　of　the　ceramics.　The　ceramics　exhibit　superior　transmittance:　T　similar　to　55%　in　the　visible　region　(760　nm)　and　similar　to　75%　in　the　infrared　region　(2000　nm),　which　is　dependent　on　optical　band　gap　energy.　In　terms　of　electrical　properties,　the　ceramics　also　possess　relaxor-like　characteristics,　low　dielectric　loss　and　suitable　piezoelectric　constants.　Due　to　Er3+,　the　ceramics　exhibit　composition-tunable　green　and　red　up-conversion　photoluminescence　emissions,　whose　intensities　are　related　to　the　crystal　symmetry.　Combined　with　good　optical　and　electrical　properties,　the　ceramics　open　up　potential　applications　in　the　electrical/optical　interdisciplinary　field,　such　as　visible　displays,　solid-state　lasers　and　transparent　electronic　devices.　(C)　2019　Elsevier　B.V.　All　rights　reserved.