The heat source and cooling of auto gearbox test platform spindle system were analyzed,and finite element model(FEM)based on analysis of thermal-stress coupling of the spindle system of the test platform was built.The heat generation rates and the heat transfer coefficient are calculated according to the design requirements and practical work situation.With the finite element method of ANSYS thermal contact,the spindle system's temperature coupled-field was analyzed.The analysis results show that the cooling structure of the spindle system is flawed,which cannot meet the requirement of cooling,so the deformation of the bearing seat is so large that it affects the accuracy of the experiment.Aiming at design examples,the measures of improving the thermal properties of spindle system are proposed,and improved structural is reanalyzed with finite element analysis (FEA).On the basis of reasonable analysis results,the equipment is improved,and the cooling effect of the improved system is good from actual measurement.The research results provide reference and basis for the cooling structural design of spindle system.