Based　on　the　micro-phase　separation　and　self-assembly　of　polymer　blends,　a　mask,　in　which　many　nano-holes　distribute　regularly,　is　developed　from　PS/PMMA　blend　film　to　fabricate　microstructure　on　GaP　surface　by　wet　etching.　By　employing　this　method　on　LED　surface,　when　the　diameter　of　the　nano-holes　in　mask　is　around　500　nm　and　the　etch　depth　is　140　nm,　the　LED　output　power　increases　by　18%　in　average.