The thermal deformation of the hydrostatic spindle is affected by the heat source during the machining process,which will affect the machining accuracy of the machine.A theoretical model of heat generation and heat dissipation of the spindle of an ultraprecision horizontal roller machine tool was established.A fluidthermalsolid coupling simulation model of the spindle was established by the finite volume method and the finite element method.The temperature field and the axial thermal error of the spindle were analyzed by considering the heat dissipation conditions in oil film area.The correctness and accuracy of the simulation model was verified by experiments.This model was used to analyze the influence of spindle speed,oil supply pressure,hydraulic oil viscosity,oil film clearance and length of sealing edge on spindle temperature rise.The results show that the temperature rise of spindle rise is increased with the increase of spindle speed,hydraulic oil viscosity and oil sealing edge length,and decreased with the increase of oil supply pressure and oil film clearance.Therefore,on the premise of meeting the performance of the spindle,the temperature rise of the spindle can be effectively reduced by using lower spindle speed,higher oil supply pressure,lower viscosity hydraulic oil,larger oil film clearance and shorter sealing edge length.