A wind turbine transformer (WTT) is designed using a 3D wound core while the transformer’s total owning cost (TOC) and its inrush current performance realized as the two objective functions in a multi-objective optimization process. Multi-objective genetic algorithm is utilized to derive Pareto optimal solutions. The effects of inrush current improvement on other operating and design parameters of the transformer such as: losses, dimensions, and weights are investigated. An approach is presented to select one design from optimal Pareto solutions based on relative improvement of the inrush current performance. Finally, this multi-objective optimum wind turbine transformer design is compared with an optimum transformer design obtained when just TOC is the objective function.