Abstract: The brush and slip ring system is an important part of generator excitation system,but the safety of generator operation is usually endangered because of overheating,so the accurate thermal analysis is the premise of structure optimization and overheating avoidance for the system.Based on the thermoelectric coupling,the three-dimensional temperature field of the brush and slip ring system was analyzed.According to the operating characteristics of the system,a thermal simulation model,which considered the heat generated by rotating friction and excitation current and convection of system,was created.By giving fundamental assumptions and corresponding boundary conditions,the governing equation of thermoelectric field was calculated coupled using Finite Element Method.The heat transfer performance and the temperature rise of the system were analyzed and the current density vector distribution of the system was shown.Then,on the basis of the thermoelectric analogy,the thermal circuit model was established from the point of view of "Road".The thermal circuit equations were solved by using Laplace Transform Method based on the complex frequency domain,and the results of thermal circuit was compared with the results of the finite element simulation.Finally,the relevant conclusions are given,which guides the structure optimization and operation safety of the system.