The　spindle　system　of　EDM　is　directly　involved　in　the　processing　process,　and　its　thermal　deformation　seriously　affect　the　processing　accuracy.　In　this　paper,　we　can　use　the　method　of　sequential　coupling,　which　based　on　the　software　of　Workbench　ANSYS,　to　analyze　the　characteristics　of　thermal-structure　coupling　in　the　spindle　system.　The　temperature　field　and　thermal　deformation　of　the　spindle　system　have　been　calculated　by　the　simulation.　And　the　results　of　finite　element　analysis　have　been　verified　by　experiments.　The　results　show　that　the　internal　heat　source　of　the　spindle　system　has　a　serious　influence　on　the　temperature　rise　and　thermal　deformation,　and　the　maximum　thermal　deformation　occurred　in　the　direction　of　X　axis,　while　the　thermal　deformation　of　other　direction　is　not　significant　to　the　thermal　deformation　of　the　spindle　system.　The　analysis　results　lay　the　foundation　for　further　improving　the　temperature　field　of　the　spindle　system　and　reducing　the　thermal　deformation,　and　it　also　provides　a　strong　basis　for　the　design　of　optimization　and　error　compensation　of　the　spindle　system.