The　design　methods　of　light　distribution　devices　used　in　illuminating　system　adopted　light　emitting　diode　(LED)　as　light　source　were　studied　and　discussed　in　this　paper.　With　the　rapid　development　of　illumination　technologies　in　the　past　fifty　years,　lots　of　novel　illumination　methods　appeared　and　applied　in　different　illumination　areas,　such　as　back　lighting,　outdoor　lighting,　interior　lighting　and　projected　display　etc.　The　key　issue　of　these　illumination　technologies　is　how　to　obtain　proper　illumination　distribution　as　designed　beforehand.　Unlike　imaging　optics,　illuminating　systems　belong　to　nonimaging　optics.　They　emphasize　transmission　and　distribution　of　energy,　not　the　imaging　methods.　Therefore,　the　basic　problems　of　illumination　area　are　responded　from　nonimaging　point　of　view　in　this　paper.　Some　novel　design　thoughts　and　ideas　are　concerned　as　well,　including　edge-ray　principle,　optical　extended　amount　conservation　theory,　maximum　concentration　rate　theory,　and　etc.　In　a　word,　a　complete　universal　method　used　in　LED　illumination　design　is　attempted　to　be　founded.