The proposal of this work is the study of the design of a three-phase distribution transformer and its optimization using techniques from natural differential evolution along with particle swarm optimization algorithms in order to minimize total losses and look at the inrush current. Transformer parameters were calculated analytically using the OCTAVE software, and the results obtained were used to define the geometry of the project and to carry out the following simulations: the first through the finite element method Finite Element Method Magnetics software, which analyzed the magnetic flux densities of the transformer core, and the second through Alternative Transient Program software for analyzing transformer inrush current. The analysis of the highest peak value of the energizing current of the three-phase transformer for the reference design and of the new optimized project is carried out by means of an approximate estimative analytical method applied to single-phase transformers and adapted in this research for use in three-phase transformers via analytical calculation and transient simulation. The verifications made through field results and measurements show that the methodology used for three-phase transformers is very efficient, minimizing losses with a consequent decrease in the energizing current.