Abstract: The electromagnetic and thermal coupling characteristics of EMU auxiliary transformers under inter-turn short-circuit fault conditions are simulated and analyzed. A 168 kV·A auxiliary transformer is selected as the research object, and the magnetic field distribution and current variation caused by the inter-turn short circuit are analyzed using COMSOL finite element simulation software. The significant influence of the fault on the electromagnetic field inside the auxiliary transformer is revealed. Based on this analysis, the dynamic evolution of the temperature field under short-circuit conditions is further investigated, and the effects of wind speed and no wind speed on the temperature rise process are compared. It is shown through simulation results that the internal temperature of the auxiliary transformer rises rapidly due to inter-turn short circuits. Under wind speed conditions, the cooling effect is significantly enhanced, leading to a lower temperature rise range and shorter duration compared to the no-wind-speed condition. A theoretical basis for the design optimization and safe operation of EMU auxiliary transformers is provided by illustrating the characteristics of electromagnetic-thermal coupling under short-circuit fault conditions.