The present invention relates to a method for optimized design of an irrigation system with tubing spans equipped with components including distributors, each composed of elements. The method comprises the steps of: inputting first data about spans into storage means of a computer apparatus where an IT product for designing the plant is stored, which comprises a database of the elements; inputting second data concerning the terminals of the last spans into the storage means; selecting elements from a group of sets of elements contained in the database; and generating, by the IT product, a list of components comprising the selected elements. Each of the sets is processed by the IT product by selecting, of all the available elements, those having mechanical properties suitable for the first and second input data and the previously selected elements for mechanical continuity of the irrigation plant.