CNC　grinding　machine　is　the　most　commonly　used　finishing　machine,　lathe　bed　is　the　foundation　of　the　machine　tool　key　parts,　as　well　as　the　guarantee　for　the　machine　tool　dynamic　stiffness.　Taking　a　CNC　grinding　machine　lathe　bed　as　the　research　object,　using　Pro/E　software　to　create　the　geometry　model,　and　using　finite　element　software　ANSYS　Workbench　of　simplified　lathe　bed　for　modal　analysis.　Through　the　modal　analysis　and　find　out　the　weak　link　of　lathe　bed　and　resonant　frequency.　In　order　to　improve　the　dynamic　characteristic　of　lathe　bed,　without　changing　job　characteristics　and　difficult　processing　conditions,　puts　forward　several　improvement　program,　again　on　the　proposed　solution　to　the　modal　analysis.　By　contrast,　determine　the　optimal　structure　of　lathe　bed　improved　scheme,　for　the　structure　design　of　lathe　bed　provides　a　theoretical　basis.