We　propose　a　simple　technique　to　improve　the　light　extraction　efficiency　of　650nm　AlGaInP/GaInP　resonant　cavity　light　emitting　diodes　(RCLEDs)　by　using　nanoscale　textured-ZnO　window　layer.　This　layer　was　performed　using　a　hydrothermal　synthesis　method,　and　the　treatment　solution　for　ZnO　texturing　growth　on　the　RCLED　surface　was　investigated.　In　addition,　it　has　also　been　found　that　the　optimum　roughness　of　the　nanoscale　ZnO　texturing　for　enhancing　the　light　efficiency　is　about　300nm.　As　compared　with　the　conventional　RCLED,　the　nanoscale　ZnO-textured　RCLED,　which　has　the　optimum　average　roughness　of　300nm,　performs　higher　external　quantum　efficiency,　a　higher　light　output　power,　and　a　narrower　spectrum　width.