Nowadays,　people　are　facing　more　and　more　threats　from　solar　UV　radiation　due　to　global　ozone　layer　depletion　and　the　ozone　hole.　Therefore,　it　is　highly　desirable　to　develop　a　fast,　simple,　and　sensitive　sensor　for　solar　UV　radiation.　In　this　work,　recently　emerging　perovskite　quantum　dots　(PQDs)　with　excellent　optical　properties　are　used　for　sensing　solar　UV　radiation.　PQDs　with　high　quantum　yields　are　protected　in　solid　paraffin　to　obtain　paraffin-PQD　composite　(P-PQD)　film.　The　hydrophobic　and　compact　paraffin　not　only　can　protect　PQDs　from　degradation　by　water　and　air　for　long-term　use　but　also　is　transparent　to　UV　light　and　thus　maintains　the　high　quantum　yield　of　PQDs.　The　P-PQD　film　shows　high　sensing　sensitivity　for　solar　UV　radiation　based　on　which　a　novel　visual　ratiometric　luminescence　sensing　strategy　for　UV　light　has　been　developed.　The　visual　ratiometric　luminescence　sensor　for　solar　UV　radiation　adopts　a　paraffin-encapsulated　red　fluorescence　PQD　(P-r-PQD)　film　as　the　sensing　unit　for　UV　light　and　a　green　luminescence　light-emitting　diode　as　reference　light.　When　exposed　to　different　solar　UV　radiation,　the　sensing　film　shows　wide　color　variations　from　green　to　red,　which　can　easily　observed　by　the　naked　eye　or　recorded　by　a　camera.　On　the　basis　of　this,　a　simple　and　visualized　solar　UV　index-reporting　system　has　been　established.　©　2019　American　Chemical　Society.