In　order　to　solve　the　problem　of　machining　stability　and　accuracy　of　the　large　diameter　Fresnel　lens　mold　processing　machine,　the　static　and　dynamic　analysis　of　the　whole　machine　was　conducted　based　on　ANSYS　Workbeach　software,　providing　reference　for　optimizing　the　design　of　machine　tool　structure.　First　of　all,　through　the　static　analysis,　the　weak　link　of　large　diameter　Fresnel　lens　mold　processing　machine　was　obtained;　Then,　modal　shape　of　the　first　six　order　was　acquired　by　modal　analysis　method,　and　the　relationship　between　the　above　structure　modal　frequencies　and　mode　shapes　was　researched.　The　results　show　that　beam　stability　is　low　and　weak,　and　the　beam　front　inner　X　stiffened　plate　needs　to　be　strengthened.　The　maximum　displacement　occurred　in　the　beam　position,　and　the　deformation　mainly　occurred　in　the　anchor,　so　it　is　need　to　improve　the　quantity　and　layout　of　the　anchor.　The　improved　scheme　is　that　keeping　the　beam　reinforcement　plate　thickness　constant,　changing　the　inside　stiffened　plate　composed　of　ten-vertical　structure　into　a　V-shaped　structure.　The　body　paragraph　need　to　be　increased　three　anchors　into　isometric　arrangement　to　provide　support　for　strengthening　stiffness　of　the　machine　tool.　©　2015,　Beijing　University　of　Technology.　All　right　reserved.