Designing gas turbines is a very complex task. It is not a linear procedure but an iterative one, composed by several phases. In the initial phase, the general geometric characteristics and estimate efficiency of the turbine are determined. This phase is known as the meanline design, and it is very important because it determines the starting point for more complex analysis. In this work we use a multi-objective evolutionary algorithm to calculate the meanline design. We consider two conflicting objectives: the number of stages of the turbine, and the efficiency of the stages.