Hydrostatic　spindles　are　increasingly　used　in　precision　machine　tools.　Thermal　error　is　the　key　factor　affecting　the　machining　accuracy　of　the　spindle,　and　research　has　focused　on　spindle　thermal　errors　through　examination　of　the　influence　of　the　temperature　distribution,　thermal　deformation　and　spindle　mode.　However,　seldom　has　any　research　investigated　the　thermal　effects　of　the　associated　Couette　flow.　To　study　the　heat　transfer　mechanism　in　spindle　systems,　the　criterion　of　the　heat　transfer　direction　according　to　the　temperature　distribution　of　the　Couette　flow　at　different　temperatures　is　deduced.　The　method　is　able　to　deal　accurately　with　the　significant　phenomena　occurring　at　every　place　where　thermal　energy　flowed　in　such　a　spindle　system.　The　variation　of　the　motion　error　induced　by　thermal　effects　on　a　machine　work-table　during　machining　is　predicated　by　establishing　the　thermo-mechanical　error　model　of　the　hydrostatic　spindle　for　a　high　precision　machine　tool.　The　flow　state　and　thermal　behavior　of　a　hydrostatic　spindle　is　analyzed　with　the　evaluated　heat　power　and　the　coefficients　of　the　convective　heat　transfer　over　outer　surface　of　the　spindle　are　calculated,　and　the　thermal　influence　on　the　oil　film　stiffness　is　evaluated.　Thermal　drift　of　the　spindle　nose　is　measured　with　an　inductance　micrometer,　the　thermal　deformation　data　1.35　mu　m　after　running　for　4　h　is　consistent　with　the　value　predicted　by　the　finite　element　analysis＇s　simulated　result　1.28　mu　m,　and　this　demonstrates　that　the　simulation　method　is　feasible.　The　thermal　effects　on　the　processing　accuracy　from　the　flow　characteristics　of　the　fluid　inside　the　spindle　are　analyzed　for　the　first　time.