A power axle is an essential part of a well-functioning train. The power axle, which is subject to both live and dead loads from the train engine, is powered by traction motors. The majority of failures and train derailments are attributed to axle failures, according to the literature. Radius runout and relief are the main areas of failure. To evaluate structural safety, this work conducts a finite element analysis of the power axle using EN 13104 standards. The inputs provided are used to determine the initial loads on the power axle, and Ansys is used to analyze the structural loads on the axle geometry. The results show that the fillet regions have a significant concentration of stress. Therefore, the design optimization procedure is used to ensure that the stress is distributed uniformly throughout the geometry. Deflection serves as the state variable, stress serves as the objective function, and the fillets at the radius relief and run-out regions serve as the design variables in this process. By defining the convergence requirements, the fillet regions are optimized using the sub-problem method. The stress for the optimized set is reduced from an initial 139–128 MPa as a result of the design optimization process, which reveals a uniform distribution of stress across both radius relief and run-out regions.