Meshing　for　finite　element　analysis　accuracy　plays　a　very　important　part　in　numerical　simulation　of　Periodic　Symmetric　Struts　Support　(PSSS).　Different　accuracy　can　be　obtained　by　different　element　sizes　or　types.　Three　element　types　and　eight　element　sizes　are　used　for　comparing　the　accuracy　of　modal　analysis　in　this　paper.　Comparing　with　the　mutual　relations　of　different　accuracy,　the　scientific　basis　is　provided　for　selecting　the　correct　mesh　size　and　improves　the　efficiency　of　numerical　calculation　in　modal　analysis.