In　order　to　improve　the　operating　performance　for　cycloid　pinwheel　reducer　in　fields　of　transmission　efficiency,　compacted　structure,　load-bearing　capacity,　and　tooth　profile　modification.　A　double-stage　multi-objective　optimized　method　is　proposed　that　considers　for　parameters　of　structure　and　modification.　Firstly,　taking　the　high　transmission　efficiency　and　small　volume　of　reducer　as　objectives,　the　constraint　conditions　included　structural　parameter　size　and　strength　limitations　were　analyzed.　Based　on　genetic　algorithm,　the　mathematical　model　for　structural　parameters　of　cycloid　pinwheel　reducer　was　established　as　the　first-stage　optimization;　secondly,　the　algorithm　of　meshing　force　and　the　deviation　between　rotated　angle　modification　and　equidistance　and　moved　distance　combination　modification　were　derived,　taking　the　low　meshing　force　and　deviation　as　objectives,　the　theoretical　model　for　modification　parameters　of　equidistant　and　moved　distance　amount　was　proposed　as　the　second-stage　optimization.　The　results　indicate　that　the　comprehensive　performance　for　cycloid　pinwheel　reducer　can　be　improved　effectively　after　optimization.