Most　photochromic　ceramics　can　back　up　post-irradiation　to　achieve　color　state　transition.　Unfortunately,　color　recovery　usually　requires　exposure　of　material　to　external　physical　fields　(such　as　light　and　heat),　which　severely　limits　the　application　as　a　convenient　energy　building　material　such　as　smart　windows.　Here,　we　report　a　kind　of　sodium　niobate　translucent　ceramics　whose　photochromic　effect　can　be　completely　self-recoverable　without　any　external　physical　field　stimulation.　Based　on　the　analysis　of　time-response　transmittance,　up-conversion　emission　spectra　and　thermoluminescence　spectra,　the　behavior　of　carrier　migration　and　trap　capture/release　in　the　process　of　self-recovery　photochromic　reaction　has　been　proposed.　It　is　believed　that　the　emergence　of　intermediate　trap　level　is　an　important　factor　to　produce　this　spontaneous　behavior.　Moreover,　by　controlling　the　amount　of　rare　earth　doping　and　designing　two　types　of　materials　with　different　carrier　behaviors,　Sm/Er-codoped　NaNbO3　ceramics　are　regarded　as　an　appropriate　candidate　for　tracing　the　time　of　light　irradiation　and　intelligent　regulation　of　smart　building　materials.　This　work　can　promote　the　fundamental　understanding　and　practical　applications　of　self-recoverable　photochromic　bulk　materials.　©　2021　Elsevier　Ltd　and　Techna　Group　S.r.l.