Aimed at the problem of wheel thermal load increase and wheel spoke fatigue caused by long time braking in downhill section of freight vehicles under SichuanTibet railway,considering the thermalmechanical coupling effect,the orthogonal test method was used to optimize the spoke of HESA type wheel of the existing C70 gondola car.The inclination angles of the two sides of the transition between the rim and the spokes,the inclination angles of the transition between the spoke and the hub,the thickness of the upper part of the spoke and the thickness of the lower part of the spoke were selected as the optimization factors,and three optimization objectives were selected,such as the fatigue strength of the spoke,the wheel mass and the static strength of the spoke according to the actual operation and maintenance requirements of the wheel.Based on the mechanical load condition according to the UIC510-5 code straight track condition,and the thermal load condition by calculating the transient thermal load of the wheel when the freight car passes through a downhill section with a super long continuous large slope under the constant speed,the static strength and fatigue strength of the three optimization wheels were checked.The wheel shape with the most optimized spoke was obtained.The results show that the three optimized wheel spokes can meet the static strength conditions,and the best combination scheme of static strength can effectively improve the equivalent stress of wheel spoke under mechanical load.The three optimized wheel spokes can meet the fatigue strength conditions,and the best combination scheme of fatigue strength can effectively improve the fatigue strength of wheel spokes under thermalmechanical coupling load.