Seedling　transplanting　mechanism　is　a　part　of　the　three　dimensional　vegetable　planting　production　line,　which　the　structural　design　has　some　harmful　effects　on　the　normal　operation　of　the　entire　production　line.　In　order　to　solve　the　problems　for　the　seedling　transplanting　mechanism,　the　TRIZ　theory　was　applied　to　optimize　the　structural　design　from　the　following　aspects:　First,　the　key　problems　were　found　by　the　functional　analysis　tool,　and　then　were　used　the　engineering　contradiction　and　the　Altshuller＇s　matrix　to　analyze　the　problems,　which　the　innovation　design　was　put　forward　under　the　guidance　of　the　invention　principles.　Finally,　the　innovative　design　scheme　was　evaluated　and　the　best　design　was　selected.　It　was　found　that　the　success　rate　of　seedlings　was　about　90%　in　practical　use,　which　verified　the　feasibility　of　optimal　design.　This　paper　provides　a　reference　for　solving　the　optimization　design　problem.　©　2019　IEEE.