The　deformation　of　constant　flow　and　closed　type　hydrostatic　rotary　table　of　heavy　duty　CNC　machine　tool　has　a　great　influence　on　the　film　thickness　because　of　its　large　diameter,　high　load-bearing.　According　to　the　circular　plate　deformation　theory　of　elasticity,　differential　equations　of　worktable　deformation　are　derived　in　the　simply　supported　conditions　when　bearing　uniform　force　of　different　locations.　Displacement　curves　of　worktable　are　obtained.　Force　and　deformation　weaknesses　of　hydrostatic　rotary　table　are　found,　which　can　provide　theory　basis　for　supporting　location　of　heavy　workpiece　machining　and　whether　oil　film　is　failure　or　not.