In order to determine the influence of the thermal deformation of the bearing on the machining precision,taking the grinding wheel spindle bearing system as the research object,the change of the oil film temperature field of bearing with the spindle speed and oil pressure was analyzed by FLUENT150,and the ThermoFluidSolid coupling model of the bearing and oil film was established by Workbench to analyze the thermal deformation of bearing.The actual temperature rise of bearing under different speed was measured by using infrared thermometer.The results prove that the spindle speed has great influence on the oil film temperature,while the oil supply pressure has less influence,and increasing the supply pressure properly is beneficial to decrease the temperature rise of the bearing oil film.The maximum thermal deformation of the bearing is located in the eccentric position at both edge of the bearing,and in the design of bearings,the heat dissipation measures should be taken to the eccentric position.The experimental results are consistent with the theoretical results,which verifies the correctness of the theoretical method