The　dynamic　model　of　a　multi-axis　synchronous　gantry　machining　center　VX32-60　is　developed　based　on　the　finite　element　method.　Both　the　numerical　simulation　and　the　modal　experiment　are　studied.　The　nature　frequencies　and　mode　shapes　are　obtained　by　theoretical　analysis　and　experimental　results.　The　effects　of　material　parameters　and　section　parameters　on　the　dynamic　characteristics　of　multi-axis　synchronous　gantry　machining　center　are　investigated.　The　design　optimization　method　of　these　parameters　is　proposed,　which　increases　the　nature　frequencies　of　machining　center　and　reduces　the　motion　error.