The hot-spot temperature of windings serves as a critical indicator for assessing a transformer’s stable operation. To accurately analyze the temperature distribution characteristics in the winding region of traction transformers, this paper proposes a simulation-based temperature analysis method for transformer windings based on fluid-temperature field coupling using a 25kV traction transformer as an example. Building upon an analysis of the transformer’s thermal characteristics and losses, a 3D simulation model was established. The finite volume method was applied to solve for the temperature and flow rate distribution cloud diagram of the transformer. Finally, the hot-spot temperature of the transformer winding under different loading rate conditions is derived by combining this simulation and analysis method. This study provides guidance for enhancing the insulation performance of traction transformers.