Abstract: A model for three-dimensional transient temperature field of induction motor was set up and the heat exchange between stator and rotor was simulated by using the concept of "equivalent coefficient of heat conductivity".The influence of temperature rise on the stator and rotor resistance was considered for thermal loss calculation.The influence of the end of stator and rotor on axial temperature distribution was also taken into account.Three-dimensional transient temperature field of the motor was simulated under rated load,temperature field with different loads was also computed;and some influence factors were analyzed.It was shown that the temperature of stator and rotor increase rapidly in the beginning,and then the rising trend slow down until reaching the stable state.In the whole process,the rotor temperature is higher than the stator temperature all the time,and the maximum temperature point is around the axial center of the rotor bar.The axial temperature difference of the rotor core is larger than that of the stator core while the radial temperature difference of the stator core is larger than that of the rotor core.The temperature of air gap decreases linearly with the increase of the thickness,and the thermal insulation effect of air gap is so strong that it makes the temperature difference of stator and rotor obvious.The motor temperature grows with the increase of load.There is no linear relation between load and temperature.The higher the wings of shell,the lower motor temperature is,whereas the descend tendency slows down;Using cast copper instead of cast aluminum as rotor bars and end rings can reduce the temperature of rotor effectively.